iPhone Storage

To clear storage on your iPad, you can follow these steps:

1. Go to "Settings" on your iPad and tap on "General" > "iPad Storage." This will show you a breakdown of the storage used by different apps and data on your device.
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3. Scroll down to the list of installed apps and review which ones you don't use frequently. Tap on an app and select "Offload App." This will remove the app from your device while keeping its data intact. You can always reinstall the app later if needed.
4. Go through the list of apps and delete the ones you no longer need. To delete an app, tap on it and select "Delete App." Additionally, you can delete other types of data such as photos, videos, messages, and unused files to free up space.
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6. If your Photos app takes up a significant amount of space, you can enable iCloud Photos to store your photos and videos in the cloud and keep optimized versions on your device. Go to "Settings" > "[Your Name]" > "iCloud" > "Photos" and enable "iCloud Photos." --> Manage your photo and video storage - Apple Support
7. If you use Safari as your web browser, you can clear its cache to free up storage. Go to "Settings" > "Safari" > "Clear History and Website Data." Please see the pic below which is self-explanatory
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9. Messages and attachments can take up a substantial amount of storage. Open the Messages app and delete unnecessary conversations or individual messages. You can also enable the option to automatically delete messages after a certain period. Go to "Settings" > "Messages" > "Keep Messages" and select an appropriate duration. Deleting attachments to messages may also help
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11. If you have music, movies, or TV shows downloaded on your device that you no longer need offline access to, you can remove them to save space. Open the respective app (e.g., Music or TV), find the content, and delete it.
12. Consider reviewing other apps and data that may be taking up storage space, such as documents, downloads, and podcasts. Delete unnecessary files or manage them accordingly.
13. After performing the above steps, it's good practice to restart

If I were you, I'd backup my iPhone to either iCloud or on your computer iTunes (Windows) or Finder (Mac), then restore the iPhone from backup. This will help clear your System Data and you'll get memory back.

The next time you buy an iPhone, you need to buy one with more memory. You clearly don't own an iPhone with enough memory to meet your storage needs and once purchased the memory on an iPhone can never be increased.

Here is a link on how to restore your iPhone from backup --> Restore your iPhone, iPad, or iPod touch from a backup - Apple Support

Not sure if this will help, but I had the same issue on my iPad. I couldn’t update the OS due to lack of space, primarily being taken up by Photo documents and data. I had deleted all the photos but it was still using up over 1 gig of space. What I accidentally discovered was that by disabling automatic updates it cleared a huge portion of that - though not all of it. I still have 200+ Mb in docs and data for Photos, but that’s way better than 1+ Gb.

When you go to Settings > General > iPhone Storage > what is taking up the most space?

Do as I recommended and you'll get back more space on your iPhone.