What is the ruling on performing a surgical operation to enlarge the chin by implanting an artificial chin, given that the chin is small and receded, which causes a feeling of inferiority?

If the congenital defect is out of the ordinary, there is no objection to treating it with a cosmetic procedure to restore it to its normal state. What is prohibited is that which is done for the purpose of seeking beauty and increasing attractiveness. It is permissible to remove a defect, as clarified by Sheikh Ibn Uthaymeen, such as straightening a crooked nose, treating strabismus, and repairing a cleft lip. However, further enhancement is forbidden.