It’s not really “both” from a space simulator perspective. There’s no option to fly down to a planet and skim the surface, there’s no option to fly from planet to planet without a loading screen (or even just to a moon), etc.
Starfield is a good RPG set in space and I’m enjoying it, but I think it’s fair to criticize that it was marketed like it was going to be a space sim by Bethesda and that’s not really what we got. If you were excited about the simulator part you are going to be disappointed.