iPadOS 13 is not iOS 12. This version has some teeth. Charlie Sorrel explains how something simple and nearly useless– Slide Over– became a must-have feature:
In iOS 13 (sic), Slide Over goes from being a useful-but-annoying novelty, to being an essential utility. Instead of only letting you dock one app window to the side of the screen, and sliding it out for a quick look or edit, Slide Over is now fully integrated.
In iOS 13 (sic), you can have multiple Slide Over panels, you can switch between them as easily as switching apps on an iPhone, you can open almost anything into a Slide Over pane, and you can easily turn a Slide Over app into a full-screen app.
Good step-by-step to get it done. Oh, it’s iPadOS 13.