How do I fix UE5 low poly landscape?

I am making car game levels with landscapes and roads. But the cliff looks low poly with vertical lines which cannot be fixed with a smooth tool. The landscape is also clipping with roads in steep areas but not when the camera is very close to road. I raised the roads a little bit but that didn’t work. Do I need to increase the resolution of the landscape to increase smoothness and no clipping with roads? If yes then how can I do it?