Is it possible to control how many and what is in a single material? For reference my use would be in game dev and I would like to control how many materials each character has such as this with 1 for hair, 1 for face, 1 for torso, 1 for legs/feet. Same goes with clothing, 1 for hair, 1 for face, 1 for skin, 1 for shirt, 1 for pants, 1 for shoes.

In CC3, each avatar can have as many as 9 different PBR maps. The main texture map is diffuse, and you can have up to 4k texture with that. If you want more detail,
you can have Normal, AO, Metallic, Roughness, Height, Glow and Blend. That is for the face. Then you can have that much or less for different parts of the character.
There are separate textures for the teeth, eyes, nails, arms, legs and body. Also for the hair, clothes pants, shirts, shoes. These characters have a lot of detail going for them.
There is also physics for the hair and dress, to make them move, when your character walks.