And what do you see, Kolmy, under the “On My iPad” menu item under iPad Storage?
I do notice that both of those are Microsoft products.
I do have a couple of PowerPoint files stored On My iPad, which do show up in PowerPoint (in On My iPad), as well as in the Files App, under On My iPad -> PowerPoint.
For Word, I don’t have any Word documents stored On My iPad.
In both, the Microsoft Apps also show an Inbox folder, On My iPad, but that doesn’t show up in the Files App.
(For PowerPoint, the Inbox folder showed a number of contained folders, until they simply disappeared from PowerPoint.)
So, I don’t know why nothing is showing up, there.
What do those Apps show in On My iPad, within the Apps?
Another place to look is the Recently Deleted folder, in the Files App.
This folder, much like the Trash on a Mac, contains files from your iPad as well as from your various Cloud providers, including iCloud.
So, you need to get Info on the files to see where they actually reside.
(Incidentally, just the files that show under “On My iPad” -> “On My iPad” -> PowerPoint, exceed the amount of storage shown for “On My iPad”, within the “On My iPad” menu item under iPad Storage.)