For certain characters, you have the option to change the Character's outfits by tapping on the Outfit icon. 
 
Outfits are more for cosmetic and does not provide any additional benefits.
 
Some Outfits can be obtained through gems, In App Purchases, Passholder, Calendar, Chest and etc.

Characters with available outfits are: Aladdin, Buzz Lightyear, Simba, Pete, Oogie Boogie, Gaston, Yzma, Big Bad Wolf, Jack Skellington, Mulan, Sorcerer' Apprentice Mickey, Anna, Elsa, Moana, Stitch, Miguel, Belle, Mickey Mouse, Minnie Mouse, Hades and Raya, Sergeant Calhoun, Merlin, Sulley, Genie, Kronk, Merida and Quasimodo, Cobra, Maui, Elastigirl, Mr. Incredible, Stitch, Robin Hood, Scrooge McDuck, Tiana, Snow White, and Syndrome.
 
More to come in the future!