https://www.gamespot.com/articles/red-dead-redemption-2-first-person-mode-confirmed/1100-6461906/

Like Rockstar's previous open-world adventure, Grand Theft Auto V, the upcoming Red Dead Redemption 2 will be playable in both first- and third-person. The third-person camera is the default perspective, as in the original Red Dead Redemption, but you can also choose to play from a first-person viewpoint, lending a much different feel to the experience.

As was the case with GTA V, the first-person perspective can help bring you into the game at a deeper level. Riding a horse in first-person gives you a new sense of perspective and place, while combat can feel more confronting. Some wacky stuff can happen, too. In my session, I was walking through town in first-person when I got run over by a horse who was trotting by. With a third-person camera I would have seen it coming.