I just found the API to find out the outfits of any player.
https://avatar.roblox.com/v1/users/1/outfits?itemsPerPage=50
(switch 1 with the player’s UserId)
For example, let’s use my player.
Result:
{"data":[{"id":662002321,"name":"Neat Fedora Look","isEditable":true},{"id":658560842,"name":"Noob","isEditable":true},{"id":658546386,"name":"OG Costume","isEditable":true}...
(Note that id represents the outfit’s id, and you would need to load the outfit using the id into the game.)