According to Apple: “iOS is the world’s most advanced mobile operating system. With iOS 13, you can now use cutting-edge technologies to build unparalleled augmented reality experiences with ARKit 3, Reality Composer, and RealityKit. Core ML 3 and the new Create ML app help you deliver personalized app experiences quickly and easily with industry-leading, on-device machine learning. Users can sign in to your apps with their Apple ID. And you can take advantage of the latest improvements to Siri Shortcuts, camera APIs, and other exciting technologies.”
Also, “iPadOS features additional technologies that take advantage of the unique functionality of iPad using the iOS SDK. With iPadOS, your iPad apps can now deliver multi-window experiences, add full drawing experiences for Apple Pencil, and contribute fonts for systemwide use”
As well as the release of the new mobile OS’s there are some new iPhones being released as well. Check out Apple’s site for the details at https://www.apple.com/au/iphone/
Catalina will be released some time in October. An article on this is at https://www.cnet.com/how-to/macos-catalina-will-ship-in-october-but-you-can-get-ready-now/
A few reference sites for this are at:
Information about the new features of the new operating systems for the different platforms is available on a variety of sources such as AppleInsider, Catalina Preview , Apple Developer - Beta 2 Release Notes as well as a host of other locations such as TechRadar that reported on the WWDC 2019 event.
One of the many significant changes are with the MacOS which will lose support for 32 bit apps and the iPadOS will have much better functionality with using storage devices for files. Something that has been a long time coming but most probably held back to avoid cannibalising the Mac sales.