It doesn’t seem to be as sophisticated as iOS implementation for quick replies to texts but it’s a step in the right direction. Google updates its default Messenger app (not Hangouts) to let you quickly reply to text messages from a notification. When the text comes in and you hit the Reply button at the bottom of the notification, it’ll take you to a full-screen quick reply view and hammer out that text. And yes, you can put emojis in there as well. If you opt to open the full Messenger app, you can also select that option there. The update should be heading your way soon.
Source: 9to5Google