Card size rdr2 and gta5?

I got rdr2 earlier and have been playing GTA 5 for some time, both online and offline, the map of gta5 seems pretty tight to me with all the years I've been playing…

I wanted to ask if someone knows an approximate number of square kilometers from the map of gta5 and rdr2?

I'm still pretty much at the beginning with rdr2, just wanted to ask about the approximate card size because rdr2 needs 2 discs (ps4)

I thank you in advance and stay healthy

Gta: 81km² without water

RDR: 75km²

But no idea whether that's true.

Okay, but why does rdr2 need 2 discs?

I could explain the size by the graphics… But I doubt it's just the graphics, thanks anyway for the answer

You will definitely get a thank you and a helpful one

Stay healthy my dear

Explains in detail that it takes 2 discs, but unfortunately not why