It can't be added with with an iOS update. Live Wallpapers work on other iPhones because they feature 3D Touch. The Xr does not. 3D Touch is hardware. It requires a pressure-sensitive layer underneath the screen. How should this be added via software?
And the flashlight / camera icon on the lock screen works with Haptic Touch which is software.
It would be possible for Apple to enable haptic-touch based live wallpapers but we don't know how the final iOS 13 will look like on the Xr. We are not Apple, just Apple users like you.
You can give Apple your feedback: www.apple.com/feedback