Apple is said to be working on a new feature for iOS 13 that will allow users to open multiple windows inside of apps and tab between them like you can on macOS (see above). Similarly, Apple is also planning to add the ability to run two screens from the same app in Split View.
New features for the Apple Pencil are also in the works, but Bloomberg did not detail exactly what those would be.
Finally, Apple is reportedly working on a new toggle for muting email threads in the Mail app (I would assume that this change will be universal, and available for all devices).
Also slated for a 2019 release as part of iOS 13 is a redesigned home screen and a smarter version of the Photos app.