Where can I find Ultimate Battlegrounds' rig?

I want to know where Ultimate Battlegrounds’ get their R6 rig that can wear layered clothings and high quality textures or how do they make it?

Probably blender or maya3d I think that’s how they’re made

I’m pretty sure its a scripting thing I’m probably wrong because I don’t know how myself

nvm, I figured it out how to make it now. thank u guys:))