You can use iCloud Photos and select “optimize iPad storage”. There are plans from 50gb to 2tb. Another option, update your photos and videos to Google Photos and then remove the least important ones for you (or large videos).
iCloud costs from $1 to $10. Google Photos is unlimited and free, however the photos and videos are compressed and the quality is reduced.
If you don’t want to use the cloud, connect a hard drive or flash drive to your iPad, and copy your photos. Then you can delete the least important ones from your iPad and free up space.