Without regard for the specific company that provides your Medical coverage, each has policies with different levels of coverage. The lower cost policies have more exclusions in order to keep costs down.
The problem is wading through the "Legalese" language of the policy.
Even if the policy specifically excludes cosmetic surgery, Medical necessity can sometimes be established with the help of a Psychologist and your primary care Dr. Both of these would be covered usually by almost any policy.