You can't!! You can try but you'll see a warning sign from Airbnb telling you that they don't allow us to add an emoji. I'm still seeing listings with emoji's in their title but they must have done this before this ban came into force.
Thank you for bringing this topic to our community!
Have you seen Joelle’s response? While emojis aren't allowed, there are other ways to highlight important information. I’m tagging @Shelley159 here, as I believe she shared some tips on this a while ago (my apologies, Shelley, if I’m mistaken 😅).