Unlocking the entire map early in Red Dead Redemption 2 is possible through a workaround.
Completion of the Blood Feuds, Ancient, and Modern mission during Chapter 3 is crucial.
Purchase the Saint Denis Times No. 47, exclusively sold in Lemoyne, to proceed.
Zoom into the cryptic text "You long for sight but see nothing" within the newspaper.
Access the cheats section in the game's menu and input the aforementioned text.
An Alert will caution about the risks of using cheats, but you'll gain access to Fog of War
Disabling Fog of War reveals the entire map, making all locations visible.