The best rpg games like Red Dead Redemption are Ghost of Tsushima, The Witcher 3 and Kingdom Come: Deliverance II. Below are 5, each with the reason it is here — and, at the end, what filtering to rpg costs you.
Filtering to RPG means you want progression — a character to build or a party to grow — layered on top of whatever else you liked.
What you get: A reason to keep going after the novelty wears off. RPGs are the genre that reliably converts hours into feeling more capable.
What made Red Dead Redemption worth playing in the first place is covered on the full list. This page is the rpg part of that answer, and only the rpg part.
The same unhurried travelling, with far better combat.
An open world where the side stories are the reason to play.
A living historical world that refuses to be convenient.
If the scale and the exploring were the appeal.
Immersive-sim western with real consequences.
Immediacy. Almost every RPG asks for a slow first few hours, and the systems that make hour forty good are the same ones that make hour one a menu.
Specifically, these are strong answers for Red Dead Redemption that are not rpg games, so they are not on this page:
The full list is on games like Red Dead Redemption — 9 picks, no genre filter.
Ghost of Tsushima. The same unhurried travelling, with far better combat.
No. Red Dead Redemption released on the PlayStation 3, but a recommendation is only useful if you can play it, so the picks above span platforms and eras. What they share is the genre and the reason.
Whether the stats are the point. In an RPG the build decides what you can do; in an action game with stats the build only decides how fast you do it.
No. The picks below span turn-based, real-time and action RPGs, and each one says which it is.
By hand. Each pick was written for the full Red Dead Redemption list first, on what the game actually does, and this page is the part of that list that is rpg — never a genre tag lookup, which is how "best racing games like Super Mario 64" used to be a page on this site.
Or read the rpg guide for where to start in the genre generally.