Each tab is a working mock of the profile screen at iPhone size (390 by 844). Pick an outfit piece and watch the thief change. Locked pieces show how you earn them.
How you earn looks (all ideas)
Achievements: each badge row gives one piece, like the Heist Mask for 1,000 chests.
Friendship: each friend's step 2 gives a signature piece, like Rosie's flower pin and Wren's ranger hood.
Quests: story quests give one-off pieces you cannot buy, like Dahlia's star veil.
Grubb's shop: plain colours and everyday pieces for gold, from 5k to 250k, with a new piece each day.
Sets: wearing a full set lights a small gold glow on the picture. It is for looks only and gives no power.
The picture in the top corner and in Elowen's greeting is made from the same outfit, so the look shows everywhere.