Not in the sense of leveling up or perks or anything like that, but it's certainly not (just) an action game. It's built largely around inhabiting a character in that world and acting accordingly. A lot of people who play that game don't even do story missions. They just wander around, hunt, buy new clothes and other stuff, and chat with random passers-by. It's role-playing in the purest sense: a sandbox that encourages and empowers you to play a role.
That's kind of a stretch imo, but ok.