Can I somehow change my character's appearance in GTA Online?
Solution 1:
With the Import/Export update Rockstar introduced the ability to change character appearance as many times as desired.
The option to do so is located in the interaction menu which can be accessed by pressing m on a keyboard or holding the back/select button on a controller. It will be under the sub-menu labeled style and cost 100,000 in-game.
Gender is not able to be changed but all other options present upon initial character creation are available.
Please note that since GTAV for PS3 and 360 is no longer receiving updates this option is unavailable on those platforms. In this case it might be possible for Rockstar support to reset appearance but I cannot find an example of this for last-gen copies.
References
Patch notes for Import/Export https://support.rockstargames.com/hc/en-us/articles/236222747
Ticket showing R* support can initiate appearance reset https://support.rockstargames.com/hc/en-us/community/posts/204246987-Change-Character-appearance