I read A software update is required to connect to your iOS device / iPhone which refers to this message as an error and talks about troubleshooting it.
I am looking to find out the Mac OS I need to run to connect to my phone. Main system is a MacPro 2010, running High Sierra. Phone runs 14.4.2. (and, I do understand if I need higher Mac OS, I’ll start to sync the phone to a newer Mac Mini.)
To be clear, I don’t want to go down the path of ‘fixing’ a message only to find the MacOS/iOS weren’t compatible in the first place.