What is the best option for restoring volume in my lower face? (Photo)

Fillers would likely be what I recommend to try first. Fat grafting is also an option here but I'm a fan of starting off with nonsurgical interventions whenever possible. You can also consider combination treatments such as fillers + radiofrequency skin tightening, for example.

Based on your one posted photo at best, a in person or virtual consultation would be required. With that in mind, I would recommend a filler facelift with a one stitch temple facelift combination. You most likely need 8 to 10 syringes of filler with the surgery fee from $10,000-$15,000. Again virtual consult required.

The fundamental Aesthetic issue is not a loss of volume, but that your mandible is small and relationship to your maxilla.
This predisposes you to premature development of jowls, loss of jawline, definition and nasolabial folds
Attempting to get the same result, as having been born, with a large mandible by adding fat or volume to the soft chair is not going to look natural.
Augmentation of the mandible may be helpful, but soft tissue solutions to a skeletal problem is always going to give partial results at best.
Getting a bigger mandible is simply too complex, but understanding that that is the fundamental problem may help accept the limitations and understand what treatments can, and cannot accomplish.
Whenever you find different providers offering different solutions it’s usually means there isn’t one single great option.
In regards to cosmetic surgery it’s often better to not have cosmetic surgery than to have bad cosmetic surgery.
Consistent high-quality outcomes are usually found on situations where the treatment can directly address the primary problem.
This is difficult in your case.
To get an idea of the impact of having a larger mandible, we can look at the face of Carmen Dell'Orefice as an example.
Those lucky enough to have been born with her facial bone structure have the upper hand.
Best,
Mats Hagstrom, MD