The main problem is that the game, like most Unity games, is not supposed to be modded. There is no toolkit for modders, and no way to install mods without resorting to external loaders that trick the executable (e.g., Unity Mod Manager on the Nexus).
As such, tutorials on how to mod Kingmaker default to tutorials on how to mod Unity games, which often means creating a DLL. This means being able to actually code in .NET, at least a little.
You can find the source of a number of mods here:
And this is the source of a very simple mod included in the bundle, the attribute uncapper:
If you understand what it does and how, then you are ready to start looking into modding kingmaker. If you do not, then you should probably follow a C#/Unity programming tutorial or three.
I heartily recommend quill18's programming howtos on youtube: