Music on iPhone 15 pro missing in iTunes

Did you install the more recent apps on your computer; Apple Music, Apple TV and Apple Devices? If so your tracks will be in Apple Music now, and you will use Apple Devices to sync with your iPhone.

If you didn't and are still using just iTunes, then perhaps this will help:

Use iTunes to sync your iPhone, iPad, or iPod with your computer - Apple Support

Regards.

Thanks, yes, that does clear it up. Take a look here; something may help:

iTunes shows no music on device - Apple Community

Regards.

Then sorry but I don't understand what you are trying to achieve. The whole point of iTunes as it applies to your phone is to allow you to add and remove tracks and other media from that phone, and that's done via the sync process. You can choose what parts of your iTunes library you sync to your phone; it's not an all-or-nothing proposition.

You'll probably need to clarify exactly what you're trying to accomplish.

Regards.