Will insurance cover filler injections?
Coverage rules are dense, so this page starts from one plain passage and reads it as a set of instructions.
The short answer
Usually not. my.clevelandclinic.org says: "Health insurance plans generally don’t cover elective cosmetic procedures such as filler injections."

What that passage asks of you
It asks you to plan on paying for filler injections yourself. It does not say what your own plan does. Your plan documents are the only thing that settles that.
Steps before you book in the Saline area
- Find your plan's document that lists what it does and does not cover.
- Look for the section on cosmetic or elective procedures.
- Call the number on your insurance card and ask directly about filler injections.
- Ask the provider for a written price before the visit, so you know the cost whatever your plan says.
Documents worth reading beside it
Penn Medicine's dermal fillers page and Yale Medicine's fact sheet on Botox and soft tissue fillers describe the treatment itself. A PMC article on non-cross-linked and cross-linked hyaluronic acid fillers and a PMC piece titled Dermal Fillers: Do's and Dont's round out the reading list.
Who to ask if the wording is unclear
Ask your insurer to explain any term you cannot restate. Then ask the provider's front desk to confirm the price in writing.