Perform quick actions on iPad

On the Home screen, in Control Center, and in apps, you can see previews, open quick actions menus, and more.

In Photos, touch and hold an image to preview it and see a list of options.
In Mail, touch and hold a message in a mailbox to preview the message contents and see a list of options.
On the Home screen, touch and hold an app icon briefly to open a quick actions menu. If the icons start to jiggle, tap Done at the top right or press the Home button (on an iPad with a Home button), then try again.
Open Control Center, then touch and hold an item like Camera or the brightness control to see options.
On the Lock screen, touch and hold a notification briefly to respond to it.
When typing, touch and hold the Space bar with one finger to turn your keyboard into a trackpad.

iPad User Guide