Syncing non-Apple Music with new iPhone 12 Pro

I set up my new 12 Pro 3 weeks ago, and was amazed at how easy and flawless this was.

Well, not quite...I now find that most of my music (all that was not purchased from Apple) and none of my playlists transferred.

In anticipation of any errors, I did back up to iCloud. The problem is: since I am accustomed to using the hated iTunes, I do not know how to restore from iCloud if I am only doing a partial restore (the aforementioned non-Apple music). My common sense tells me to just go to iTunes and use an older backup; this would have all the data I need, but it probably would not be the correct iOS iteration. I cannot go back to the old Xs for help as I just last week erased it and passed it on.

I would appreciate any advice you might offer as to 1) how to do a partial restore blindfolded over WiFi, or 2) if I am just better off going with the iTunes version, where I could pick and choose what needs to be restored.

Thanks much!

Georgia

PS. I have roughly 300 books .epub, in Apple Books, only a few of them purchased from Apple Books. ALL of the books (Apple and NON) transferred without a hitch. What is so special about Music???

And this IS iPhone 12 Pro. Had to choose 11 from the list as 12 was not there.