30 fps sounds very low to me for 1080p!
I play in 3440x1440 and have also the 2080 TI and Ultra Settings, max Traffic/ Shadows, … in the Air there are ~50 fps in most Areas.
Only if you be at some huge city places with much traffic, you can have less than 30 fps
I think you must have a problem with your machine, with my 2080 no ti, I have 40 fps in tokyo, very dense city with lots of clouds, otherwise I have 50 FPS on average