iPhone storage full pop up but I used 63.1 GB

You are paying for iCloud storage, not phone storage.

The storage on an iPhone cannot be increased, it is a fixed size.

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 - Apple Support

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

Manage your photo and video storage - Apple Support

Manage your photo and video storage - Apple Support

Clear Other storage on your iPhone or iPad - Apple Support

Clear Other storage on your iPhone or iPad - Apple Support

Outside of removing apps/data on this phone, you would need to get an iPhone with a greater storage capacity. The newest 14 models, can come with up to 1 TB of internal storage.

Please go back and read my post again, I've provided you with the answer.

If you need more storage and can't delete anything else on your phone, your only choice is to buy a phone with a larger storage capacity.