iTunes version on iphone

Things such as iTunes Store and the Music apps are just part of iOS and don't have specific version numbers. Since your signature shows you have iOS 12.1 that means you have the latest version.

Is there a specific reason you need this information?

iTunes on the iPhone is not like iTunes on the computer. It does not manage anything except your purchases. All it really does is allow you to make purchases from iTunes. iTunes on the computer does all your managing, except for apps. You have an App Store on the iPhone for handling management and purchase of apps.

Apple does not even report a version number for those apps in Settings, like other apps show, since, as indicated earlier, they are integral to the iOS, and cannot be updated separately anyway.

You say that Apple wanted to know the version, or am I misunderstanding what you have written? If Apple wanted to know the version, were you attempting to get some support for a problem? If that was the case, and you were using iTunes on the computer, then they wanted to know the version of iTunes on the computer, not the iPhone.

You don’t.

What matters is the iOS version.

12.1 being the latest.

iTunes doesn't run on your phone, it runs on your computer.