iPadOS? Yes. iOS? No.
Or: you can do what you want trivially on an iPad, but you can’t on an iPhone. The closest you can come on the iPhone is the usual app switcher (swipe up from the bottom).
I wouldn’t expect Apple to ever support multi-window multitasking on an iPhone. Within rounding, 0% of iPhone users want this sort of thing. And, of the remainder, 80% would be unhappy with any reasonable implementation and only ever use it in extreme circumstances.
The screen is just too darned small for that sort of thing. Most apps already require careful design just to cram everything onto the small screen. Maybe on a ProMax? But you’d be left with less real estate for each app than you have on the mini full-screen, and it just doesn’t seem reasonable to require developers to support micro-sized windows for such an edge case.
b&