So in my games, I don't often use sound fx. In Call of Cthulhu I occasionally showed some scenes from film a film version of a HPL story. So I made playlists but most often I would put on a bunch of happy pop jazz on the start of a game in the real world. Possibly some classical or some jazz for more low key investigation music might be a good one. The final one was all darkwave ambient mythos inspired tracks which are pretty good for any dungeon environment too.
upbeat pop 20s
https://www.youtube.com/watch?v=gsxo1agB6SU&list=PLiPQbzF37X-5ubyRNs3r6m0AOnM0B6_kE
darkwave ambient horror
https://www.youtube.com/watch?v=pyFjXaKiJLk&list=PLiPQbzF37X-70sP2E83A1K8Fldl4eMnXd&index=1
let me know if these broken or anything
I will add new stuff I find below
Feel free to add more and comment