Who can receive SkinVive by age?

The mistake here is reading an approval as permission for anyone who wants smoother skin. Age is the line the published information draws first, so start there.
The age line, as published
The important information published at news.abbvie.com describes SkinVive as "an injection to improve skin smoothness of the cheeks in adults over the age of 21."
The short answer is adults over 21. You can read the original wording in the FDA approval announcement and check that nothing has been paraphrased away.
Reading the line cautiously
That one sentence names an age, an area and a goal. The age is adults over 21, the area is the cheeks, and the goal is skin smoothness.
A younger person, or someone who wants treatment somewhere else on the face, is outside what that statement describes. Do not stretch the sentence to cover your case.
Glam's take on SkinVive as skincare in injectable form is consumer coverage, and it does not change the age in the approved use.
An age check is not an eligibility check
Do not confirm your own eligibility from an age check. A trained injector who has examined your skin decides whether it fits you, and a consultation is where that happens.
Before you book in the Mt Olive area, ask the provider to tell you in their own words what the approved use is. A clear answer is a good sign.
Over 21 is where screening starts
Being over 21 means you can ask whether the treatment is an option. It does not make it right for you, and a provider who treats age as the only screen is skipping the part that matters.