GTA V and GTA Online are coming to next-gen consoles in the second half of 2021, with upgrades planned for the PS5 and Xbox Series X.
GTA 5 and GTA Online Next-Gen Details
As Ahmad notes, the next-gen versions will offer "technical, visual and performance upgrades", suggesting a new version of Grand Theft Auto 5 could offer improved textures, loading times, or even ray-tracing.
As far as GTA Online is concerned, the new platforms will get exclusive content (which will also come to PC). There will also be a standalone version of GTA Online that launches exclusively on PS5 and will be free to PlayStation Plus users for three months. That's to keep, as well, so you won't need to buy it once the three months is up.
When GTA 5 launched in 2013 (which makes me feel old), it offered the likes of online heists. Those didn't make it to the game until it came to Xbox One and PS4 in 2014, alongside a new first-person mode.