With a 1060, when I really started gaming, it was pretty hard to have very good settings and get 60fps. Overwatch on Ultra ran at about 50fps (100% render scale), GTA 5 on the "nvidia optimized" settings was almost always 60fps but would drop down to 30fps sometimes. With a 1080, everything is always 60fps, even on Epic with some modifications (fog distance I think has the biggest effect). My attempt to max out the settings to just get 60fps has led to slow framerates (30-40) during hero selection and the "play of the game" intros, though. Only sometimes, it's very strange. (With the nvidia-optimized settings, this doesn't happen, though. But the graphics aren't quite as good in-game.)

Overall you should basically be able to pick any GPU and play any game at 4k. I would like to get another monitor for 1080p/1440p at 144Hz, but don't have anywhere to put it, so 4k@60 is enough for me. IPS panels are nice for everything except gaming, so I live with the compromise when playing games. Screen refresh rate is not the limiting factor in my ability, not by a long shot.