Thanks for getting back to us with that information, craigst2. It's helpful.
QuickTime will not open .mov video -- Have a look at Jon Walker's reply to another user having the same issue. Check under the "More Info" tab to see what codecs are being used. You may need another application in order to play the movies you've recorded on your iPhone 11 Pro Max.
Using HEIF or HEVC media on Apple devices -- If you'd like to keep the camera from recording with either format, you can take photos and videos using older formats. Scroll down to "Capturing this media" for the information. There's also great information under "Working with this media" if you wish to continue to use HEIF or HEVC.
Let us know what you discover when you can.
Cheers!