I bought storage for my phone but it didn’t change what do I do??

No, you bought iCloud storage. iPhone storage is a fixed size and can't be changed.

What's the difference between device storage and iCloud storage? - Apple Support

Here are some helpful articles that can guide you on how to free up storage space on your phone.

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

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

Manage your photo and video storage

Manage your photo and video storage - Apple Support

Clear Other storage on your iPhone or iPad

Clear Other storage on your iPhone or iPad - Apple Support

What do you mean you can't do anything? You can do a lot of things, just not increase the storage size on your phone.