In order to make meshes (specially heads) to be slider enabled, its an incredible 'destructive' thing to do, since the game engine doesn't allowfor proper export of the existing meshes, so I basically had to 'redo' all heads and that's why they look different from the ones on the base game. But to achieve a slider it's a type of mod that changes the Soldier Animation Tree, so any mod that does the same will be incompatible (none that I'm aware of though). Aside from that I also made revealing versions of some of the armor parts (it's a WIP, and eventually I may refit more parts at some later point). This mod was initially developed to simply add a slider Customization option, to be able to have soldiers look more or less muscular.
\SteamLibrary\steamapps\common\XCOM 2\XComGame\Mods To install the mod just extract it to your game installation mod folder:
REMEMBER, THIS MOD IS STILL IN DEVELOPMENT!