On Playstation's game page for GTA Online it says that the free standalone version can be claimed only on PS5 console store. So its not free to claim for everyone from the
Grand Theft Auto Online (PlayStation®5)
GTA Online PS5 version is free to keep forever at launch
GTA V,' 'Online' PS5 Xbox Series X|S New Features | Hypebeast
Grand Theft Auto V
Grand Theft Auto Online (PlayStation®5)
GTAV and GTA Online out today on PS5 – PlayStation.Blog
Grand Theft Auto V Standard Edition PlayStation 5 57864 - Best Buy