Can I back up old and new iPhone on iTunes? If so, how?
I never was able to get everything from my iPhone to transfer to my new one. Can I back up this old iPhone to iTunes and keep my backup of my new iPhone?
iPhone 7, iOS 13
Yes. For iTunes backups only encrypted backups contain all data. Non-encrypted backups leave out health data and passwords.
Make sure your phones have different names so you can tell the backups apart (Settings/General/About - Name.