perhaps I’m misunderstanding, and I do hope to be as wrong as possible.
if I design a character with different shape keys, say an athletic character and a fairly large one. I have a chest plate male piece that is fitted to that character.
When I export my character from something like a blender I export with morph targets (or shape keys) that allow the character to be those two different shapes I created.
The armor itself, as far as I am aware, has to be exported in those two different instances as well.
I’ve never come across armor or equipment that can be export not as a static mesh.
If you could send me in a direction where I can learn, I’d happily do so.