The more you increase the crf the more visual loss you have.
Personally, I found out that CRF 17-18 is visually lossless for x264 at FHD.
Just to be clear, are these the right settings for YouTube 1080p 60 fps?
To follow their recommendations you need to use fixed GOP. It can be done by disabling scenecut: scenecut = 0. Also, keyint should be the half of video FPS.