I upgraded my plan to have more room but I can’t take pictures because it says I don’t have enough space on my phone. What do I do?

You bought iCloud space, that will not increase the storage space on your phone, it is a fixed size.

The difference between phone storage and iCloud storage -

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 and iPad - Apple Support

Manage your photo and video storage - Apple Support

Clear Other storage on your iPhone or iPad - Apple Support

Your devices physical storage cannot be increased, so what you have purchased is iCloud storage. However, there are steps and settings to have iCloud storage help your phones physical storage limitations, to a point. Take a look at What's the difference between device storage and iCloud storage? - Apple Support