How to install itunes on iphone x

If you mean that you deleted the iTunes Store app and want to reinstall it,

Restore a built-in app that you deleted

1. On your iOS or iPadOS device, go to the App Store.
2. Search for the app. Make sure that you use the exact name of the app. Find the correct name of built-in apps.
3. Tap  to restore the app.
4. Wait for the app to restore, then open it from your Home screen.

If you have an Apple Watch, restoring an app to your iPhone also restores that app to your Apple Watch.

iTunes runs on your computer, not your phone.

What, exactly, are you trying to accomplish?