email split screen on iPad

The native Mail App always presents a sidebar in Landscape view. This isn’t a Split Screen view - but might resemble a 30/70 split.

If you do have a Split Screen view, place your finger one the centre of the central divider (you’ll see a little grey drag bar) and drag the divider to the edge of the screen - then release; your split-screen view will become full-screen.

You can manipulate other screen views in a similar way. To transform a Slide Over view, to Split Screen, use the grey drag-bar at the top of the Slide Over Window; drag downwards and to towards the side of the screen. As the view changes, lift your finger.

You can also change a Slide Over to a Full Screen view. This time, using the same drag-bar, drag to the top-centre of the screen, then release.

You may find these overview Apple video guides to be helpful:

After viewing, you’ll be ready for the additional Multitasking Guide:

https://support.apple.com/en-us/HT207582

The iPad User Guide for iPadOS is also a rich source of information. Here are links to both the downloadable and online versions of the Guide:

https://help.apple.com/epub/ipad/en/

https://support.apple.com/guide/ipad/welcome/ipados

I hope this explanation and additional information is helpful in resolving any difficulties you may be having with Multitasking features of your iPad.

Place the cursor exactly between the two apps and drag to the side.