I have a laptop with a vanilla RTX 2070, and I play on my ultrawide monitor at 1080p, so I guess that's at 2520x1080. Yes, I know it's supposed to be 2560, but we're talking about an actual 16x9 game, so it truly plays at 2520x1080.
Anyway, at max settings at that resolution, I see smooth framerates with zero noticeable dips. I've yet to benchmark it, but it's smoother than the PS4 Pro and looks better at the same time.
I haven't tried 4K (with or without DLSS 2.0), but the ultrawide experience is good enough that I don't really feel inclined to do so.