NO STORAGE

If you thought buying iCloud Storage was going to magically increase the amount of storage on your iPhone, you are misinformed. Buying iCloud Storage ONLY gives you more space to sync data in the cloud. There is and never has been any way to increase the amount of storage on your phone which was fixed at purchase.

Read this link about the difference between iCloud and iPhone memory --> What's the difference between device storage and iCloud storage? - Apple Support

If your phone is low or out of storage, you must delete things you don't need, which can include Photos, Apps, Music, Video, Messages, Files, Email, etc. Next time you buy an iPhone buy one with more memory as it appears the phone you own, doesn't meet your storage needs.