How to move iTunes library & iPhone backups from El Capitan to a new Mac?

I'm setting up a new MacBook Air (macOS Tahoe) and replacing my old MacBook Pro running OS X El Capitan.

All of my music and local iPhone backups are currently stored in iTunes on the old Mac.

• How do I transfer my iTunes library so that it opens correctly on the new Mac?
• How do local iPhone backups and syncing work on new Macs now that iTunes has been replaced?

Thanks in advance for the guidance!