It really depends on the game, graphical settings and stuff like that.
Racing games and rigs aren't very common anymore (Were they ever...?)
So stuff like this is pretty much uncharted territory.
I believe a 3070 is enough for 50-60 or more fps in most sim games, with details on medium-high at 1440p (for 3 monitors)
If it was a single monitor, i'd expect around 4k ultra 80-90 fps.
so make that 1440p ultra to around 120-130fps, 1440p medium-high around 160-170
divide by 3 and you get 50-60 or so fps on each monitor.
Obviously the math totally doesn't work like that in the real world, but I guess it a rough approximation.