Let me know if you are one of those people that have an iPod without the iTunes, then I can document complicated steps of getting iTunes, pulling the music off of the iPod, loading the music into iTunes, then you can sync the iPhone XR like the instructions above.
And of course, I do not have my iPod music library on my PC in iTunes. I've got iTunes installed on my PC. Just need those complicated steps of pulling the music off my iPod and loading its music library into iTunes.
The common way provided by Apple Inc. is using iTunes or iCloud. But you could only back up purchased history for music from iPhone and restore it to your iPod by downloading those songs from iTunes Store