iPhone 8 not syncing with iCloud

I don’t have a computer. I have iPhone 8 and iPad Pro with OS 18.5. Because I have not been able to sync with iCloud, my storage on my iPhone is full. I keep deleting as many photos and attachments to texts as I can, but it doesn’t affect the amount of data stored on the iPhone. I have worked with an online Apple tech person who could not solve the problem, even after restoring original settings. Any ideas? Thanks.