Will upgrading from 16GB to 32GB of RAM noticeably improve gaming FPS?

Not really. Doubling from 16 to 32GB won’t give a meaningful FPS boost in almost any game today, since most use 12-16GB at most. It only matters if you’re running background apps, streaming, or playing heavily modded titles like Cities: Skylines—and even then, gains are small. RAM speed stays the same, so no performance delta there.