I have music on CD. If I use iTunes to transfer music other data on iPhones will be erased. Can I transfer music without iTunes to iPhone directly from CD?
iPhone XR, iOS 12
No, you cannot transfer directly from CD to the device. See Recover your iTunes library from your iPod or iOS device - Apple Community. Pull everything into one library, then you can wipe and reload the device.
tt2
You can use iTunes to add a specific song, or album, or selection of songs, to your iPhone.
Select the songs. Control-click or right-click on the selection to access the contextual menu. Select Add to Device﹥Your iPhone.
or:
Select the songs. Click on the ellipsis (…) in the track name field on one of the selection to access the contextual menu. Select Add to Device﹥Your iPhone.
Then not everything gets synced, but just that selection gets transferred.
I suspect the OP is seeing the erase and sync warning that you get if you attempt to add media to a device that was previously associated with a different iTunes library. It should not be lightly ignored.
tt2
transfer of media to iPhone
