First, you should know the official meaning of emoji. Many mistake emoticon with emoji, but emoji are actual pictures instead of typographics. It comes from the japanese word e (絵, picture) + moji (文字, character) and they are smileys used in electronic communications, apps and web pages.
The original and default emojis are the ones in the middle of the text, like they were a font. And that’s a reality, they are text characters with a big problem: compatibility. When an author of a message picks an emoji from a keyboard, it is normally encoded in a non-graphical manner during the transmission, and if the reader do not use the same software or operating system (iOS / Android / Windows..) for his device, the reader's device may visualize the same emoji in a different way. For example, instead got a heart emoji you see a weird character like ☐
Although is not possible to do it as text character, we’ll get as close as we can making a keyboard and sending the emojis through it using the COPY & PASTE feature and integrating on GBoard to send them like stickers. The size is bigger because is not possible to include the emojis next to the text. It has to go separately and as an image. The good thing is that the emojis are more detailed, so we took this as advantage. Default emojis are small and need to be simpler, but as our emojis are images, we draw them high quality and handmade.
See it on this sample:
This will be as default emoji next to text 
This is the full image you can share. 