My iPhone 13 does not list Dolby Atmos as an option how can I get it on my iPhone?

This does not work. As the OP said, there is no “audio” option listed after tapping music. If you search for Dolby atmospheres in the settings, it does not exist.

this is also true for an iPhone 12

Choose how to listen to Dolby Atmos on your iPhone or iPad

1. Update your iPhone or iPad to the latest version of iOS or iPadOS.
2. Go to Settings.
3. Tap Music.
4. Under Audio, tap Dolby Atmos.
5. Choose Automatic, Always On or Off.

About Spatial Audio with Dolby Atmos in Apple Music