Storage on iPad says full.

iCloud is not a substitute for storage on a device but may help in limited ways. See About storage on your device and in iCloud - Apple Support

including the following:

Free up space on your device

You can make storage space available on your iPhone, iPad, or iPod touch when you use iCloud Photos and turn on Optimize Storage. Or you can remove content from your apps—like photos, music, and Podcasts—or delete the apps that you're not using.

Also note that iCloud Photos is a syncing service. Any photo you delete from a device where iCloud Photos is turned on will also be deleted from iCloud and from any other device connected to iCloud Photos. You can potentially reduce the storage space required on a device by turning on Optimize Storage. See: https://support.apple.com/en-us/HT204264

Apple does not currently offer cloud-only storage for photos. If that is what you want or need, you may want to explore 3rd party options such as Google Photos or Dropbox.

iCloud is used to backup data, not a replacement for local storage. If you’re running out of local storage take a look at Settings >General >iPad Storage

You’ll see some tips on creating space and any apps you can off load. Photos can be put in the cloud and local storage can be saved by allowing them to be downloaded as needed (optimize iPad storage).