What filler/treatment can help the dimpling and sagging of my chin/lower face? (Photos)

A combination approach would give the most improvement. I recommend fillers for the lines themselves and to build anatomical support with Sculptra for collagen building. Ultherapy is a great skin tightening device, but works best in combination with other treatments like J Plasma, RF treatments, lasers, microneedling/PRP, salt facials, Cosmelan for skin tightening and improve skin tone. I recommend getting a formal evaluation with an expert. Best, Dr. Emer

There are multiple treatment options both surgical and non-surgical. At age 54, sometimes a short incision facelift and laser skin resurfacing can provide the best results. Non-surgical options include Botox to relax the mentalis muscle, fillers to diminish grooves at the corners of the mouth, and again, some kind of laser skin resurfacing, chemical peel, or radiofrequency microneedling to improve skin texture. 

Fractora RF is the top of the line skin tightening treatment and is noninvasive. Some patients need both a lower face/neck lift and fractora to resurface the whole face, neck and chest which is a great combination and works wonders.

Based on the photos, your issues seem to be a combination of volume loss, muscle hyperactivity, and skin laxity. The best results would be seen with combination treatment which includes fillers, Botox/Dysport, and skin tightening with radiofrequency (Thermage). With regards to the fillers, Sculptra could be used to stimulate collagen production and improve underlying face volume while a hyaluronic acid based fillers like Restylane Refyne/Defyne could be used to improve the lines themselves while preserving normal facial expression.