Hi
In steam you can set it to install on a different drive (steam setting storage).
I then put in a new cache using the option in MSFS and I moved the community folder to a different location using the MSFS options. So they all live on my F drive (once full of 2020 mods and now a barren landscape)
I also installed Steam to that drive as well - but you don’t have to have the client on the same drive as the games.