Thanks for the question. It is important to first find out the underlying cause of the lisp before suggesting any treatment option.
The most common type of lisp is frontal lisp, where the tip of the tongue protrudes between the front teeth and obstructing the airflow. There is also palatal lisp, where one rolls their tongue too far back and touches the roof of the mouth and dental lisp, where the tip of the tongue pushes against the teeth.
Common causes of lisp include tongue placement and tongue tie. If it is due to tongue tie, a jaw surgery is not needed and a minor tongue tie surgery would do.
You are recommended to bring your child to a paedodontist/oral surgeon so that he/she can do a thorough dental condition to advise the possible treatment option.
