Kingdom Come Deliverance is a very CPU intensive game. CPU determines your FPS. GPU adds eye candy, mostly. I hear new video cards are changing this to some degree. Your GPU is only cruising because the CPU can't send frames fast enough. I doubt your RTX 2070 is having issues but check GPU temps to be sure and use latest drivers from Nvidia. If CPU is getting too hot it will throttle back making things worse, so check CPU temps as well. A CPU with hyperthreading will likely do better but you only have 6 cores/6 threads.
Close any unnecessary programs running in background to free up CPU if you can. Overclocking may help some but I wouldn't expect too much. The only real fix is a better CPU or live with it. If it's playable I wouldn't worry about it. Games that are GPU intensive may see less CPU use. It goes back and forth depending on the game.