My chin is quite round and a bit recessed
How can i get a square chin?
Open mouth chewing, before I practiced this my chin was round, narrowish, and just dull. But a few a weeks in, I noticed it became wider and just overall broader. To describe it if you put a before and after of me you would see a distinctive difference.
This could possibly make a difference in your bone formation, but it'll be difficult because in your case you have a recessed chin but THAT'S OKAY, power to the users.