To give you an idea of what you can expect with a Intel 5ghz CPU I ran your settings at 3440 X 1440 in SOTTR.
Your SOTTR settings are even higher than the highest preset. I also added the settings I used to play the game less RT.
I have more than two RTX 2080 tis. The reason I don't run two of them together now is that I don't need the performance. My 2080 ti are doing fine. It is my CPUs that are the issue and even a i9 10900k is not an upgrade for me.
I have seen quite a few i9 10900k videos and I have come to the conclusion that it depends more on the quality of the silicon and the cooling solution of the 2080 ti used in the tests weather it can outperform other 5ghz Intel CPUs in games. So to me only if you need the cores and want the 5ghz plus gaming experience do you need a i9 10900k.
If I needed a CPU now I would get a i7 10700k since it is a cheaper i9 9900k and available.
The reason I don't need more performance than a single 2080 ti now is with my 5ghz Intel six cores I am bottlenecked at 1440p in most AAA games with my RTX 2080 ti running at 2040mhz and above. Basically my 24/7 2080 ti overclock. This will get worse with the nex gen cards but with them comes HDMI 2.1 and with that 4k 120hz on my OLEDS. These bottlenecks come in at around 130fps but my OLEDS do 120hz so not a problem. It would be a problem if I would have stuck with my 144hz 1440p monitor.
At 3440 X 1440 the bottleneck is even less of an issue but you can see it creeping in on my score with my play settings.