Has anyone found spells/abilities or feats or class traits or weapon types that allow your character to use Wisdom/Intelligence/Charisma instead of Strength/Dexterity for weapon modifiers/rolls (damage & hit)?

Warlocks can get Pact of the Blade at level 3. It allows them to use their charisma modifier for their melee attack rolls

pretty much any spell that does damage or makes a weapon

The Oath of Devotion Paladin gets Sacred Weapon at level 3, which allows to add the Charisma modifier to attack rolls.

Its not clear from the description if this is on top of the Strength or (for Finesse Melee Weapons and Ranged Weapons) Dexterity modifier, or instead of the later.

Its probably additionally to the Str/Dex bonus.

https://bg3.wiki/wiki/Sacred_Weapon

Druids and Nature Domain Clerics can select the Shillelagh cantrip that uses Wis for attack rolls and has 1d8+Wis damage but only works if you have a club or quarterstaff equipped. It's a bonus action so you can cast it and attack in the same turn. Any class can also select this cantrip via the Magic Initiate: Druid feat at level 4 etc. but it will still use Wis.

Since you mention weapons specifically, the following is maybe not what you meant, but arcane spellcasters like Wizards and Sorcerers have access to offensive cantrips, such as Fire bolt and Shocking grasp that can be used for ranged and melee range attacks, respectively. Since these are cantrips, you can use them infinitely so they're kind of equivalent to wielding a weapon. Shocking grasp has a secondary effect of inhibiting reactions so an enemy can't initiate an attack of opportunity. Related ranged cantrips are Ray of Frost and Chill touch which do slightly less damage than Fire bolt but have a secondary effect, reducing movement speed and inhibiting healing, respectively.

Wizards use Int for attack rolls, Sorcerers uses Charisma. Damage is determined by the damage die of the cantrips but these cantrips scale with character level so they're capable of decent damage and will still scale even if you multiclass. For example, Fire bolt initially does 1d10 damage but this increases to 2d10 at level 5 and I think will scale again later to 3d10. Any class can select these cantrips via Magic Initiate: Wizard or Magic Initiate: Sorcerer. Warlocks can also select the Eldritch blast ranged cantrip that uses Cha for attack rolls and does 1d10 force damage, scaling to 2d10 at level 5 and so on. Each die is rolled separately, though, giving you more chances to hit and the ability to hit multiple enemies, making this cantrip different to the Wizard and Sorcerer ones. Again, this cantrip is also available via the Magic Initiate: Warlock feat.

Level 2 Warlocks can enhance Eldritch blast with Agonizing Blast, which adds Cha to the damage, and Repelling blast, which pushes back the enemy by 4.5m. I've found repelling blast to be very powerful for pushing enemies off ledges or back into an area I've locked down via a crowd control spell like Hunger of Hadar or Plant Growth.

Character level ?!?!?

Not to my information.

If you want your spells to get stronger, you have to increase your characters multiclass spellcaster level.

Spellcaster level increases like this:

Cleric + Druid + Bard + Wizard + Sorcerer + floor(Paladin/2) + floor(Ranger/2) + floor(Fighter with Eldrich Knight/3) + floor(Rogue with Arcane Trickster/3) = Multiclass Spellcaster.

Where "floor" is the mathematical function that rounds down (and ceil() rounds up).

Note that Warlock does NOT increase your spellcaster level. They are treated completely separately and you probably shouldnt multiclass them.

So if you for example have a Wizard(1)/Paladin(3)/Fighter[Eldrich Knight](5), then your spellcaster level would be 1+1+1 = 3.

Note also that this means the only way to have access to levels of your spellcaster level is to have levels in Wizard, since their ability to learn spells from scrolls depends upon their multiclass spellcaster level.

So a Cleric(8)/Wizard(1) could already cast one level 5 spell, but the Cleric wouldnt have access to level 5 spells just yet. The Wizard could, though. Assuming the character would have Int 4, the Wizard could prepare up to 4 level 5 spells and cast any one of them when he chooses to.

Cantrips are special compared to non-cantrip spells. WoTC has a Sage Advice compendium at https://media.wizards.com/2015/downloads/dnd/SA_Compendium_1.01.pdf that states:

"If a character has levels in more than one class, do
the character’s cantrips scale with character level or
with the level in a spellcasting class? Cantrips scale with
character level. For example, a barbarian 2 / cleric 3 casts
sacred flame as a 5th-level character."

There was also a Twitter/X post about this by the lead rules designer: https://twitter.com/JeremyECrawford/status/503306866831929346?lang=en

I am also playing a multiclass Bard/Wizard and can confirm the cantrips scale with character level in BG3. A multiclass Wizard's ability to learn and prepare any spells up to level 5 in your example is debatable in strict DnD5e, as per https://dmsworkshop.com/2017/04/09/things-you-didnt-know-about-dd-multiclass-spellcasting/ :

"This is the point where most people go wrong. According to page 164, when you are determining which spells you can learn or preparing a list of spells, you treat each class separately, completely ignoring the multiclass spellcasting section entirely. If you have one level of druid, it doesn’t matter how many other spellcasting levels you have, you prepare druid spells as though you were a 1st-level druid.
...
Only the spell slots you gain are shared between all spellcasting classes."

I'm inclined to agree with that post because that's how I initially interpreted the multiclassing rules I found at https://5thsrd.org/rules/multiclassing/ but I'm not experienced in DnD so *shrug*.

However, I can confirm my Bard/Wizard in BG3 is able to learn Wizard spells on the spell slots they have access to, which makes multiclassing in BG3 much more enjoyable. Hopefully this is an intended feature and not a bug that Larian will fix later. Given Larian's decision to home brew a number of other things in BG3, I'm pretty optimistic this was intentional in the name of fun over strict rule adherence.

Edit: also when a multiclass Wizard levels up, they can only select spells based on their Wizard level, not character level. It's their unique ability to learn spells from scrolls that gives them the outlet above which is unique vs other spell casters.

Hmm interesting so Cantrips are more useful than I thought.

Wizards (and other spellcasters) are not supposed to be able to change spells as quickly as they can in BG, but otherwise its as the PHB specifies:

"When you find a wizard spell of a level for whicvh you have spell slots and you can spare the time [... you can copy it into your spellbook]"

PHB pg 114

In BG you can change spells at any time but you lose the slot and have no access to the new spell till you sleep. In BG3 you can swap spells any time out of combat, you do not lose a slot, and you immediately have access to the new spell.

I already knew all that ?

Did you mean BG3 when you said BG? If so, then I misunderstood.

Oh I'm sorry.

Yes I meant BG3 when I just said BG.

That's from the Wizard class description? For a single class Wizard, the spell levels they can know and prepare correspond to their spell slot progression. So whether you consider 'know and prepare' or spell slots separately or together, a Wizard 1 will only be able to know and prepare 1st level spells.

I don't have the PHB so I can't quote from it but I think the SRD should be the same with respect to multiclassing. According to https://5thsrd.org/rules/multiclassing/#class-features, which corresponds to the official document at https://dnd.wizards.com/resources/systems-reference-document, 'know and prepare' and 'spell slot progression' are treated independently:

"Spells Known and Prepared. You determine what spells you know and can prepare for each class individually, as if you were a single-classed member of that class"

Therefore, a Cleric 8/Wizard 1 will only be able to know and prepare the spells that a Wizard 1 can, namely 1st level spells.

"Spell Slots. You determine your available spell slots by adding together all your levels in the bard, cleric, druid, sorcerer, and wizard classes, and half your levels (rounded down) in the paladin and ranger classes. Use this total to determine your spell slots by consulting the Multiclass Spellcaster table.
...
If you have more than one spellcasting class, this table might give you spell slots of a level that is higher than the spells you know or can prepare. You can use those slots, but only to cast your lower-level spells. If a lower-level spell that you cast, like burning hands, has an enhanced effect when cast using a higher-level slot, you can use the enhanced effect, even though you don't have any spells of that higher level."

As already covered, spell slots progress based on character level but this section states nothing about being able to know or prepare spells of a particular level. That aspect is already covered by the 'Spells Known and Prepared' clause.

Nothing in the multiclassing section explicitly mentions anything about a Wizard's ability to copy spells, although I'd be inclined to consider a copied spell to be a known spell. However, even if you treat them differently, a Wizard 1 wouldn't be able to cast 2nd level and higher spells, even if they could copy them.

Thematically, the restriction makes sense to me. A Wizard 1 single class is a novice Wizard and Wizards acquire their spell casting via studying. Gaining many levels in a divine spellcasting class such as Cleric shouldn't magically, pun intended, grant the character knowledge and ability to cast higher level Wizard spells.

Mechanically, though, I find the restriction overly onerous, which is why I like how it is in BG3. Loosening the restriction makes a multiclass Wizard much more flexible whilst IMHO not making them overly powerful since the Wizard class level still restricts the maximum number of spells they can prepare and their class feature progression such as arcane recovery and the total character level restricts the available spell slots. In BG3 specifically, it allows me to create a Bard that can prepare some spell slots with the flexible spell selection of a Wizard, whilst not having all of the full power of either a single class Bard or Wizard.

a bard can also take some spells from other classes so could have magic missile from a wizard or hex from a warlock... its only 1 spell evey 6 levels or so but if you are only dipping into multiplayer to get a certain spell its generally better to just stay bard