My apple iPad is grossly enlarged how can I fix it

If the screen is zoomed in try double-tapping the screen with 3 fingers and see if that zooms it back out - and if it does set Settings > General > Accessibility > Zoom 'off'. If it doesn't zoom you back out try triple-clicking the home button and see if that turns it off, and if it does you can then change what a triple-click does via Settings > General > Accessibility > Triple-Click Home (or Accessibility Shortcut depending upon the iPad's iOS version) .