Is it possible to download full iCloud backup for iOS 13?
Yes what you ask is generally and technically possible and also requires some skill and/or funding to perform.

If you intend to access your account, I’d read over the Apple terms and conditions carefully. The US license has language that prohibits anyone from accessing the service (which has the data) through automated means including scripts.

Then decide if you need a lawyer to make sure you are not in violation of the terms before you access your data with a tool or script like the commercially available tools like Elcomsoft phone breaker suite.


https://www.elcomsoft.com/eppb.html


I would instead use Apple’s iOS and hardware to download your full backup unless you’re sure you need other means and have evaluated the legality and risk to access the data in a way that’s potentially not licensed.

The terms also explain what a “full backup” is and is not - so you might need to use a backup method other than iTunes based on what full means to you.


https://support.apple.com/en-us/HT207428
https://www.apple.com/legal/internet-services/icloud/en/terms.html



  The following content is not included in your iCloud backup: content purchased from the iTunes Store, App Store, or Apple Books, media synced from your computer, and your photo library if you have enabled iCloud Photo Library