the skin feature is only change whole part, and it is impossible changing each part like glasses, headgear, shoe and gloves
How do you make part-cosmetic system for game?
You can combine any skinned parts at runtime in the engine. You can also preview multiple skins for stuff like glasses, headgear, etc by using the Skin view's Pin feature in the Spine editor: https://en.esotericsoftware.com/spine-skins-view
There's also this project that shows an example of organization here:
http://esotericsoftware.com/spine-examples-mix-and-match
Depending on the runtime several skin mix and match examples are also available.
Hope it helps!