GTA Online allows for players to customize the appearance and gender of their characters — once. However most other online games nowadays (which incorporate custom characters) have mechanics which allow players to alter or re-customize their in-game avatars in case some new options are added later on or if the player just simply wants to change their face. This may appear as a game mechanic found in the relevant game's virtual world, such as a magic mirror or barber shop, while in other cases players must contact the game's support staff to trigger the character-creation process on that given avatar once again.
GTA Online didn't have any such option available for quite a while, however after popular demand, the support method was implemented. If you contacted Rockstar support, telling them you want to change your character's appearance, they would have you log out of GTA V, and the next time you log in with the character you want to re-customize, you would be shown the character creation screen before spawning into the world. While there wasn't any official set limit to this, obviously you couldn't go around changing your character's appearance every other day. However you weren't necessarily restricted to a single alteration either. One thing the new system did not allow for though, was a change of your character's gender.
