Brand new I pad is not charging

iPadOS 15.6 includes an explicit fix for iPad mini6 known charging issues. Ensure that you have updated to this version.

Releases notes can be found here:

About iPadOS 15 Updates - Apple Support

iPadOS 15.6

iPadOS 15.6 includes enhancements, bug fixes and security updates.

• • TV app adds the option to restart a live sport game already in progress, and pause, rewind or fast-forward
  • Fixes an issue where Settings may continue to display that device storage is full, even if there is space available
  • Fixes an issue that may cause braille devices to slow down or stop responding when navigating text in Mail
  • Fixes an issue in Safari where a tab may revert back to a previous page
  • Fixes an issue where iPad mini (6th generation) may not detect a charger or other USB-C accessory

Follow the steps at the following document:

If your iPad won't charge - Apple Support