You can view all open windows for an app, including those in Split View and Slide Over.
From an open app: In the Dock, tap the app you want to view.
Swipe up from the bottom edge of the screen if you don’t see the Dock.
From the Home Screen: Touch and hold the app you want to view, then tap Show All Windows.
For an app in the Dock, swipe up from the bottom edge of the screen if you don’t see the Dock.
Note: If you touch and hold an app for too long, all of the apps begin to jiggle. Tap Done or press the Home button (on an iPad with a Home button), then try again.