Hi Whitelightning14,
Thank you for using the Apple Support Communities.
We understand that you have concerns about high cellular data usage and we're happy to help!
If you haven't already done so, check to verify that the Apple Music app is taking up the most of the cellular data usage: Check the cellular data usage on your iPhone and iPad. Also, “If you don't want an app to use cellular data, you can turn it off for that app. When cellular data is off, apps will only use Wi-Fi for data.” If you have a poor Wi-Fi connection, then turn off Wi-Fi Assist: About Wi-Fi Assist.
If you're still experiencing high cellular data usage, then turn off Background App Refresh. Turning off Background App Refresh will prevent an app from auto updating in the background. See Switch apps on your iPhone, iPad, or iPod touch. If you want to limit your data usage Use Low Data Mode on your iPhone and iPad.
We hope this helps.
Take care.