I’m no expert, but in general using my probably misguided understanding, I’d say no.
Kinda depends if you are main-thread limited or not. If the primary thread is limited, reducing cores to speed it up might help the main thread, but you may be adding to the things that core needs to do by eliminating the other cores, so do you really gain anything?
Sounds like a trade off to me, if it can process faster, but has more things to process, do you gain anything?
Watch your per core readout in task manager while running MSFS and see what if anything is maxing out. Also use the dev mode tool to see if you are main-thread or GPU limited.
My Ryzen 7 3700X has a base clock speed of only 3.6GHz 4.4 max. It runs MSFS comfortably but also has 8 cores. But seeing as the main thread is comfortable, that’s what keeps things moving.
In general, if you have a good CPU, the GPU being the limiting factor usually means that no matter what you won’t max out the CPU as long as it’s able to deliver more than the GPU can process. You want more CPU than the GPU needs, but once you go over that limit, you aren’t going to gain anything further.
Edit: Just realized with Intel you might have integrated graphics. Which throws a whole different set of considerations into the mix. Firstly being, you probably have a pretty beefy CPU, but can it serve as both CPU and GPU at an acceptable performance?