What I mean is custom skins that a player can switch on the go without needing to authenticate with Mojang, and other players that have your mod installed can see the custom skin as well, Like how optifine capes work.

I'll look into it. While I'm at it maybe I could add other skin features like capes. I can't promise anything though.

Im on 1..20.1 and everytime i try to change my skin game crashes

I'll look into it. While I'm at it maybe I could add other skin features like capes. I can't promise anything though.