Running the actual numbers on the map size claim
Rockstar said Vice City is roughly twice Los Santos, and the full map is about three times RDR2's. People are treating those as the same claim and they are not.
RDR2's playable area is commonly put around 75 square km. Three times that is somewhere near 225. GTA V's whole map including the countryside is usually estimated around 75 to 80 as well, with Los Santos proper being a fraction of it.
So the city being double Los Santos does not mean the city is huge relative to the state. It means the state is enormous and the city is a dense chunk of it. Those are very different games to play.