GoKawiilApple's first foldable is real, and its extra screen real estate required the company to offer new ways to interact with apps, including letting iPhone owners use multiple apps at once for the first time. Based on what Apple showed during the "surprise and shine" event, the experience is similar to the iPad, but with rearranged sidebars that keep everything in reach.
To accommodate the iPhone Duo's 7.6-inch inner display, Apple redesigned apps to make menu buttons easier to reach with one hand, moving the dock and menus to the side of the phone. Apps can also adopt more iPadOS-like designs when the Duo is open, for example, showing more interface elements and messages in Slack. That also translates to more space on the home screen. The Duo technically displays two home screens' worth of space when open, allowing you to access more apps at once or use larger widgets.
Apple
Like an iPad, the Duo allows apps to be run side-by-side and resized on the fly in Split View, making it possible to drag photos between apps, or reference info in one app while inputting it in another. The Duo's extra space enables new features in Apple's own apps, too, offering a live feed of the rear and front cameras during FaceTime calls, or letting you get your kid's attention with the front screen while you're taking a picture of them in the Camera app.
Apple
Apple's ambient display feature StandBy is also updated on the Duo since the phone can be partially folded to prop itself up. Using either the inner or outer display, the Duo can act as a clock, a photo frame, or a live feed of the weather. Naturally, what the phone displays can also be customized. Once the iPhone Duo is updated to support the USB-C Apple Pencil, iPad-exclusive software features for marking up images, drawing, and taking notes will also be available on the Duo later this year.