How to transfer music from iPad to iPhone without re-selecting?

Purchased new ipad with 18.6.2. Spent spent several hours combing thru 200 gigs of music on Mac, dragging and dropping 30 gigs of music into the ipad.

Then purchased new iphone, and I would like to add the exact same music choices into the Iphone without spending the time again. Cant seem to select the music on the Ipad in any manner at all to duplicate. Any solution?

[Re-Titled by Moderator]

Original Title: How to