Do I need to purchase more gb for music storage

You cannot purchase more storage for your phone. It will always have the amount it came with. To create more space, you must delete photos, messages, apps, etc.. Be sure to save important photos and data to your computer or external drive. Check these links...

How to check the storage on your iPhone, iPad, and iPod touch - Apple Support

Clear Other storage on your iPhone or iPad - Apple Support

How would we know? We don’t know how much storage you have on your phone and how much music you plan to keep on it. You can stream music without having to download it if you have an Apple Music subscription.