It has 100+ components that comply with Apple’s Human Interface Guidelines.
By clicking on the button below you’ll be sent to the Apple Design Resources website where you’ll have access not only to the iOS 13 XD UI kit but also to official UI kits elements for macOS, watchOS and tvOS.
Not sure why but the files downloaded are in .dmg format, not .xd.
Don’t be alarmed though, as you’ll be able to use .xd files once you download and launch the .dmg file on your machine.