When you want to share something in iOS 13, you will now get a new screen of share options that include contacts that you may want to share this item to based on a variety of factors.
This new sharing page also shows you apps that make sense for that specific type of file, so you don't need to sort through a bunch of apps to get to the one you want.
You can still add favorite apps and even turn off some suggestions, but we haven't found options to change the contact settings.
Apple also adds in some new options if you swipe up for easier access to the functions like copy, and for other options and settings that the share sheet opens up. Like on iOS 12, these vary based on the app and file you are trying to share.
On iOS 12 the share sheet doesn't include contacts and it doesn't allow you to get app suggestions in the same way. You can edit the apps to use, but that's it.