Depends on the game. For simple graphics games like CSGO, the gpu won't be doing much of anything, even a 660ti is good enough there to allow very high fps, but in really intense, lifelike games like BF1 or CoD with high details or better, the cpu will be taking a break. And that's not if adding things like hairworks or ray-tracing that can hit the gpu for over 100fps.
The 2060S is a really good match for anything 1080p, and will even do 1440p decently.