While I have figured out how to change resolution (there is a file where the game folder is installed labeled Kao with a gear), I can't seem to figure out how to get it fullscreen. I did try setting Windowed = 0, but it still appears in a window. Has anyone figured out how to enable fullscreen?

For games like this, I use this tool. https://github.com/Codeusa/Borderless-Gaming/releases

Borderless Gaming runs windowed apps in borderless fullscreen. Then I just use Joy2Key for proper Gamepad mapping support.

I did also find that dgVoodoo2 works to fix the screen issue, as well, after I posted this. Still, both work and are good to help with issues.
Now if only I could figure out how to fix the tank controls of the first game...

Add "CameraRelativeControll = 1" to kao.ini to change from tank controls to a modern camera relative control scheme.

That did it. Thank you so much! Now note for anyone trying this, I put it under the "rasterizer" tag in the kao.ini file. I don't know if that makes a difference. Also, I found out you enter the "CameraRelativeControll = 1" EXACTLY as RibShark typed. If you do it wrong, it won't launch the game properly and you get an error message.

found a fix. ingame when you go to controls you can change almost any with yo controller (only my uh triggers dont work)

For Kao 3 : just go to the game folder => media => user.ini
and uncomment the "-fs" line (or add "-fs" if there are no -fs line). Then launch the game and it should be fullscreen. It worked for me.

Same for Kao 2.
Used dgVoodoo2 for Kao 1.

Don't know.