Right now, Automatic Backups requires connecting to a Cloud Storage provider, of which only 3 are supported, and iCloud is not even one of them. However, "Backup Now" supports saving backups to an Files.app location, which supports any cloud service that is integrated with Files.app.

What I would like to see is Automatic Backup have support for closing a location in Files.app (either local on device, or cloud service provider).