Popular dataminers Tez2 и WildBrick142 have released new info on GTA 5 update for next-gen consoles. According to them the game will have a Character Transfer feature that will move your GTA Online characters from PS4 and Xbox One to the new version.
Also the dataminers have found a new clothing category called Gen 9 Exclusive and exclusive clothing items for transferring characters. It seems this will be one of many bonuses Rockstar Games is planning for returning players on PS5 and Xbox Series.