Manual backup free app

iOS/iPadOS devices don’t natively support backup to external storage devices. Natively supported backup methods are to iCloud or to a PC/Mac running iTunes or Finder:

How to back up your iPhone, iPad, and iPod touch - Apple Support

Supported methods offer full system backup - consisting of data anddevice settings.

It is possible, however, to use a third-party App to backup data (not device settings) to a variety of external storage options - including third-party Cloud services and network storage. One App that comes readily to mind is FileBrowser Professional by Stratospherix:

https://apps.apple.com/gb/app/filebrowser-professional/id854618029

You would be well advised to review the extensive online Manual and help files to determine suitability for your needs.

https://www.stratospherix.com/products/filebrowserprofessional/filebrowser-professional-user-guide.php

Dansan89 wrote:

How can I backup my iPad Pro data to a USB C 1TB Thumb Drive

you don't this is how you back up How to back up your iPhone, iPad, and iPod touch - Apple Support