This can be done with additional software. I use FileBrowser for Business and this provides many features that turn the basic file capability of the iPad into desktop class file handling. For instance it can access your photos and you can create a backup job to copy to external media. When this job is run subsequently, it will only copy the changes, thus saving time.Is there any way to backup my iCloud Photos to an external hard disk?
On the Mac i can backup my photos using time machine. But on the iPad there is only the possibility to back them up manually (selecting every photo) and copy them to an external hard disk.
I’ve been using FB for Business for a few weeks now and once you get over the initial learning curve, it’s my go to App whenever I use the iOS file system. It’s worth mentioning that the speed of copying data from the iPad Pro to external media is very slow. This is an iOS fault that Apple needs to address and is discussed here in other threads.
I hope this helps.