Starting with iOS 10, Apple has super-sized all of the Emojis that you send and receive via iMessage whenever they’re used without any complementary text.
Because the Emoji experience on iOS 10 feels a lot more like Facebook Messenger’s sticker system now and not everyone’s on board with it, a new free jailbreak tweak called Littlemoji can be used to return them back to their pre-iOS 10 size.