GTA roleplaying is pretty big. FiveM, the platform for GTA roleplaying servers (now under ownership of Rockstar Games), has surpassed its previous concurrent player record during the New Year week. At one time, there were over 300,000 players playing in GTA V roleplay servers.
FiveM are essentially modded versions of GTA Online, but the game is hosted on other servers rather than directly modifying GTA Online directly. Now that Cfx.re (the team running FiveM) is under direct ownership of Rockstar, these roleplay servers are now more legit than ever. These servers allow for more interesting interactions between its players, more than just killing and harassing each other with silly weaponry.
Rockstar Games will be releasing the highly-anticipated GTA VI next year. Whether that version of GTA Online will incorporate roleplay elements as seen in FiveM remains, or if the Cfx.re team will make different servers just for roleplay like how they are operating right now, remains to be seen.