system
A chat on subreddit /r/NoStupidQuestions
human
This is a dumb question, but I don't know code well and am trying to learn. 

Are they literally putting the emoji in the formula? Or is it [woman] + [Medical] = lady doctor?
gpt
I'm gonna test

Without zero width joiner: 👩⚕️

With zero width joiner: 👩‍⚕️ 

It seems it is literally just the two emojis glued together with the zwj. Whatever system is running to display the text on your screen knows that these two (👩⚕️) with this zero width joiner in between (‍) should render as 👩‍⚕️.