The Messages app has undergone a lot of changes in iOS 10. Much of the evolution is hidden behind two icons, just to the left of the iMessage text field (just to the right of the camera icon).

There’s a lot to play with here. Just be aware that some of the actions will send without a specific confirmation. So if you are going to experiment, you might want to warn the person on the receiving end. For example, if you tap the Digital Touch icon (two fingers on a heart), then scribble out a sketch or two finger tap, the scribble or kiss will be sent immediately, without any staging. This is not a complaint, just an observation.

All that said, the linked post from Rene Ritchie talks you through some of these features. I love this path for Messages, looking forward to seeing more of this.