Set up iPhone 14 as new phone or restore from backup?

Used an iPhone4 until 2016, then used Android for 7 years until purchased a new iPhone 14 recently. I have my old iTunes files from the iPhone4 on my PC. When I plugged the iPhone14 into the PC and started the setup, it asked me to choose between:

Set up as new iPhone

or

Restore from backup

It gives a backup year of 2020, but in 2020 I did not own or use an iPhone and did not do a backup in 2020. I don't know what it will back up -- iTunes from iPhone4 or new files from iPhone14.

If I select "Set up as a new iPhone," can I later sync my iTunes from the folder created using my iPhone4? I updated iTunes yesterday so it is up to date. I'd like to sync my iPhone 14 with the iTunes but don't know which of the two options (above) to choose.

Another possible complication is that Apple required me to create a new Apple ID on the iPhone 14. Apple Support had me add the old AppleID, so the phone has both of my Apple IDs listed.

Thanks for any help.