I’ll try to keep it relatively simple;
Your CPU is a 10 core / 20 thread CPU, which work very well for heavy productivity workloads (like rendering and video editing). Processes like this can fully utilize all those cores and threads.
Most games (this sim included) don’t work like that, since there is a main process (the main thread) that can only run on a single core/thread of your CPU, that keeps all the other processes that get outsourced to the other threads in sync.
You could buy a 64 core / 128 thread AMD Threadripper processor for 4000+ dollars, and it won’t give a single FPS improvement, it will likely perform worse, since its single core speed is lower than your CPU.
So, if you bought that CPU for MSFS, you massively overspent, since the game can’t (and will never) fully utilize it.
Good part is, is that your CPU is pretty fast on single core performance, so it’s not bad by any means.
So since the main thread limits your FPS, your CPU is simply not able to feed data to your (massively powerful) GPU. The GPU can only render a frame once it’s prepared by the CPU.
So especially at 1080P, your GPU will be chilling around 20-40% load.
You can easily go to higher resolutions at the same detail level, since the CPU can only deliver a certain amount of frames.
So if you bought that system specifically to run MSFS at 1080p, you massively overspent, and that hardware is basically wasted.
If you also run other games, and are doing some productivity workloads, it’s a great system.