How do I scan multiple pages in the iPad mini 6?

Scanning multiple-page documents with your iPad is straightforward. This support describes the process:

How to scan documents on your iPhone or iPad - Apple Support

An equally simple process is to use the Files App. Open the App, then navigate to the location/folder within which you wish to save the document - creating a folder if required. From this location, touch-and-hold (i.e., long-touch) and hold an empty area of the screen to expose a menu; from the menu, tap Scan Documents. Scan each page, one at a time, until you’re finished - then tap Save.