There’ll be a time when you’ll switch from Arthur Morgan to John Marston in RDR2 and if you are confused how you can fast-travel during that time, then here is how you can do that.
Go to the Marston Ranch at Beecher’s Hope, which is his home, and enter this room:
When you enter the room, in the corner, you’ll find a map on a small desk, like this:
And that is how John Marston can fast-travel in RDR2, you can find the list of places you want to go and pick one!
Let us know if you have any queries, thank you!