magnifier square on 7th gen ipad

It sounds like you have activated Magnifier. Go to Settings>Accessibility>Magnifier. If you used the Accessibility Shortcut, you can turn that off in Settings as well. While in Settings>Accessibility>go to Accessibility Shortcut, set that to None, but tapping to remove any checkmarks.

As far as I know it can. I know that Magnification is one of the Accessibility shortcuts. Under the Magnifier setting, it states "when enabled, triple-click the to button to start Magnifier." That would depend on the device I guess, but for my iPad Pro 11, without a home button, you triple-click the top button. Zoom magnifies the entire screen, and the OP stated it created a box.

Chris, might you be thinking of the triple-click of the Home Button - that activates the device camera, in full screen, as a magnifying tool?

Absolutely - the triple-click shortcuts differing in function from the three-finger tap, that triggers the “zoom” window, as reported by the OP.

My pleasure to help. Problem now resolved?

Settings > Accessibility > Zoom - set to OFF, or refine the settings to meet your needs.