What if you can’t free up your iPhone storage, what do you do then?

Ok so I have not had storage space on my iPad or on my iPhone and each and every time I try to delete something, the storage would just come back. It’s basically all the way full now and I can’t do nothing. I have no clue what to do and really need help in this. Half of my pictures are gone too may I add and I can’t update my iOS cause of the storage. I just updated the iCloud storage but it’s like nothing changed. Help me please!