Can't Get Music to Sync to New iPhone

[Hrothgar]

I recently replaced by iPhone 12 with an iPhone 15 pro max. I can't get all of my music to sync to the new phone. It's brought over about 100gb, but I should have close to 500gb on the phone. When I listen to music, many of my albums are missing or are missing songs.

any suggestions about how to fix this?

 

[Kottu]

Sync your 12 with a mac and move from mac to iPhone

 

[Hrothgar]

The music files are already on the Mac.

 

[Kottu]

And syncing Mac and iPhone is not moving your music?