Just a quick sanity check for the premise to avoid getting into the concept and then finding no way forward.
The basic idea is that the player character is a robot, with several base frames available, a variety of heads and trim parts ala the usual visible equipment in RPGs, and then a pair of sliders to go from neutral at center to masculinized or feminized and (separately) bulky or slim, and a few color pickers and a decal layer used to finish it off. I know how I'd do the geometry in Blender with multiple morph targets and if worse comes to worst only having a few skins to pick between is hardly uncommon in gaming, but can Godot do that kind of thing in a reasonable way? Ideally without eating too much frame rate so unique NPCs can be procedurally generated and (possibly, later) multiplayer models don't need to be traded around and cached before a scene instance starts up, just drawn from a common library of geometry and shaders with the unique settings applied as needed.
I've done far more modeling compared to my limited programming experience, and any RPG is a huge project, but a character editor like in City of ____, Champions--, or Star Trek-- Online just needs a lit room and a starting set of morph targets, and should be an ample supply of shiny new hotness to keep me motivated to learn what I need to give them environments to be seen in and plot lines to act out, and to keep the character parts flowing to see in them.
