About RDR2, i wouldn't call it a competitor as it's nowhere to have the same style as GTA.
Also Multiplayer exists as an official feature only in GTA 4 (removed later from PC in future patches) and GTA V, which are kind of recent games when Mafia series are existing since 2002, same era when GTA moved to 3D, it's Mafia that couldn't compete, but it's still enjoyable