Required Mac OS for a given iOS version

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.

The software update being prompted for installation is not an update to a new release of macOS, but rather an update to the software macOS uses to connect to an iOS device.

New versions of macOS include updates to this software, but the software can also be downloaded and installed onto an existing version of macOS without updating macOS. Therefore it is safe to install this update without updating macOS itself.

These updates used to be new versions of iTunes.app which could be updated separately to macOS (and new versions bundled with new macOS). With Finder now taking responsibility for iOS device communication, the updates are provided through macOS software update despite not being new versions of macOS (similar to Safari, Command Line Tools, etc.).

I get these update messages too - when I have not updated the os or iOS….. I use to cancel them but got tired of seeing them pop up when I connect my phone so I just update. Coincidentally I just got one yesterday and updated. I can never tell what the update does - iTunes seems the same and so does everything else. If I choose to not update, my syncing and everything else still seems to function.