Sorry, no, not possible.
Your iCloud backup is effectively incremental. Each time the iCloud backup process runs, changes are backed-up to the existing iCloud backup.
iCloud does not maintain multiple full backups of any single device. This strategy, whilst lacking the functionality that you seek, provides a fast/efficient backup of your device(s).
If you wish to keep multiple full backups of your iPad, you’ll need to use a PC (with iTunes installed) or Mac (with iTunes or Finder) as appropriate the installed version of macOS). Having created a device backup, it will need to be manually archived prior to creating a new full backup of the device. In addition to lack of automation, the time required for each backup will be considerable - in direct proportion to the amount of locally stored data.
Be aware that neither iCloud not iTunes backups include installed Apps or externally sourced media. References to Apps are saved - permitting automatic reloading of Apps from the App Store if they remain available. Externally synchronised media must be reloaded from source.
I hope this insight and clarification proves to be helpful.
