Backup Fails on Older iPad Air running iOS 12.5.7

I have an older iPad Air running iOS 12.5.7 (yeah, it's that old!) and I would like to back it up to iCloud so I can use that backup to set up a new iPad I just purchased. Unfortunately, I'm getting the error message when trying to use the "Back Up Now" function.

I suspect it's because it's running the old iOS, but I remember from a while ago that this model of iPad was no longer supported and I was unable to install new iOS software.

Is there anything I can do to create a backup of this old iPad and use it to set up my new one?