Apparently if you have gboard, some specific words followed by space will give you a sticker on the third suggestion above the keyboard. I'll put a list of all the ones I
Gboard adds a bunch of hilarious and disturbing emoji mash-up stickers (APK Download)
Cook Up Your Own Custom Emoji Stickers with Gboard for Android « Android :: Gadget Hacks
Stickers for Gboard - Apps on Google Play
Creating a Custom Gboard Sticker Pack – A Guide for Android Newbies
How to use Google's Mini selfie stickers in Gboard | PCWorld
Stickers for Gboard - Apps on Google Play
Gboard may soon be able to convert text into stickers - Times of India
Cook Up Your Own Custom Emoji Stickers with Gboard for Android « Android :: Gadget Hacks
Gboard Now Lets You Create Custom Stickers Using Two Emojis | Beebom
Gboard Can Now Make Custom Emoji Stickers Out of a Selfie
Gboard for Android offers emoji-to-sticker suggestions - 9to5Google
Google tests new feature for Gboard that delivers sticker recommendations based on text - PhoneArena
How to Add Sticker Pack on Gboard - HardReset.info
Gboard for Android update will let you add Biimoji and stickers to chats
Gboard updates: sticker and Bitmoji support added - The Verge