(Replying to other thread to bring it into its proper home in this thread)
I wouldn’t worry about the HDD right now since you have a 500GB NVMe drive as well. If you have a favorite, drive-intensive game then put it on the SSD. Other stuff can go on the HDD and it’ll be fine.
You’re probably fine with 16GB. I come up close to that in select games with some background stuff running (Discord, Steam, Firefox, etc) but I haven’t seen myself go over. And Windows will reallocate as it needs. If you see a great sale on some RAM then by all means go for it (I have 32GB myself) but, again, it’s not anything to need to worry about right now or think you’re playing at some disability this afternoon. If you’re curious, you can download something like HWMonitor and see what your RAM usage is like under normal circumstances: in a game with a some background processes.