Yes, typically lipoma excisions are covered under insurance. Whether or not you will have to pay any out-of-pocket costs depends on what your deductible is, whether or not you have met the deductible, and if the surgeon you choose accepts your insurance or the amount paid by your insurance. It's useful for the surgeon to submit for a preauthorization on your behalf to see if your insurance will approve the procedure. If they approve it, there is still no guarantee that insurance will pay, but they likely will pay something. How much is paid varies depending on your insurance. If it sounds confusing that is because it's the game insurance companies play: they may or may not pay, they will not tell the doctor in advance if they will pay or how much they will pay, they may require "reminders" to pay, and ultimately may take many months before sending payment (at times over a year to pay the bill). Going to an "in-network provider" does not mean you pay nothing, and often "out-of-network" providers try to match or beat your out of pocket costs as compared to staying in-network. Ask the doctor up front what the estimated costs are, and what happens if insurance does or does not pay. That way you know what your best and worst case scenarios are in terms of cost.
Lipoma removal is a covered benefit with most insurance carriers. Consult with an experienced and expert board certified plastic surgeon to understand your options.