Fat injection is a good option for non-surgical facial rejuvenation. However, there is a certain level of unpredictability as always less than 100% of the fat survives long-term, so touch-ups may be required for some patients.
Age itself does not play a major role for fat injections. Overall physical health is a much more important factor than chronological age. A plastic surgeon not only will evaluate your neck and face anatomically, but will also review your medical history, and interview you to help determine if you are an appropriate facial fat injections. After speaking with a plastic surgeon specializing in facial cosmetic surgery can he/she advise you on your cosmetic options. Best of luck.