I need my iPad mini 6th generation set back to factory reset

Assuming that you can still access your iPad, you can erase all data and settings from iPad settings. This procedure differs from a Factory Restore (that requires access to a PC or Mac) only in that the factory restore process will also (re)install a fresh copy of the most recent version of iOS/iPadOS that your iPad is capable of running.

For iPadOS15.x or later

Settings > General > Transfer or Reset iPad > Erase All Content and Settings

For iOS/iPadOS14 or earlier

Settings > General > Reset > Erase All Content and Settings

If you do wish to perform a full Factory Restore, installing a fresh copy of iPadOS, you will unavoidably need access to a PC (with iTunes installed) or a Mac (with iTunes or Finder - as appropriate for the installed version of macOS). If you don’t have access to a suitable computer, the Genius Bar at your local Apple Store or Apple Authorised Service Provider (AASP) will be delighted to assist.

Restore your iPhone, iPad, or iPod to factory settings - Apple Support

You can:

1. Backup the content of that iPad6 to iCloud, using these instructions:--> How to back up your iPhone, iPad, and iPod touch with iCloud - Apple Support
2. Use this procedure to erase all data and restart from scratch:--> What to do before you sell, give away, or trade in your iPhone, iPad, or iPod touch - Apple Support
3. Restore your data from the previously made backup:--> Restore your iPhone, iPad, or iPod touch from a backup

If you don't care about data currently stored on that device, you can skip step #1 and step#3 (by performing just step#2) .

Regards

Giulio