The Wardrobe feature allows you to preview cosmetics on your own character model without actually equipping them. Any cosmetics equipped while in Wardrobe Mode will go on a mannequin that spawns in front of you instead, and you can walk around and look at the mannequin from from any angle.
You are the only one that can see your own mannequin
To toggle Wardrobe Mode, use the wardrobe command
To exist Wardrobe Mode, you can type the command again or simply walk away and the mannequin will despawn.