Enhance submental angle? (Photo)

When there are multiple questions about the same case (with very good answers), I would suggest that you seek in person consultations.  Good luck!

Thanks for your pictures.  This is tough in my opinion to achieve your desired result.  There all of treatments that can be done but will they yield your desired result.  You definitely need a personal consultation to get the best recommendation. 

To make that cervicomental angle change in a young person with little subcutaneous neck fat, you need a submentoplasty procedure. This is where any subplatysmal fat is removed and the neck muscle are tightened at the cervicomental transition.

 The photographs demonstrate a weak chin profile, and fatty deposits in the neck. A small chin implant can be inserted at the front of the mandible to give added projection to the chin to help with the jawline. A small amount of fat removal on the neck with a few sutures in the platysma would be required to give an improved submental angle. No skin removal is required. For many examples of this combination, please see the link and video below

While there are many approaches to improving that area, really only one can create the type of definition you are seeking. To get a crisp angle, like the one you drew, requires working on the fat and gland layers underneath the muscles of the neck, as well as the muscles themselves. This can all be done through a small incision hidden behind the chin. In your case, there is no excess skin, and no excess fat in the layer that liposuction would address. To see in example of how this approach can turn out, look at the review by user newchinSTL 

Over the internet guesses are KyBella injection , ThermiTight RF, Lipo, fat grafts to chin, chin implant, fillers to chin...