I'm 30, BMI is 23, and have always had a turkey neck. Would a neck lift improve my jawline or are there better options? (photos)

Based on your presentation, it looks that you have obtuse neck due to low inserting muscles and presence of fat both on top and underneath the platysma muscle. This is usually a family trait? Anterior neck lift is procedure that will address both issues and create stable, long lasting result in your age group. All is done through a small incision underneath the chin in twilight anesthesia. No other procedure, in particular the non-invasive ones, will address the problem that is purely anatomical. Good luck.

options for you include facetite (more advanced than thermi) or Necklift. do you want longer term? neck lift, fillers, lasers will be your best option despite age.
There are many options for jawline contouring:
1) implants
2) fat or filler injections along the bone
3) botox for masseter hypertrophy or platysma muscle/neck bands
4) ThermiRF/J Plasma/Renuvion/InMode FaceTite for internal heating
5) Thermage or Ultherapy skin tightening
5) PDO Novathreads or instalift threads for lifting
6) Neck or facelifting surgery
7) VASERlipo with or without platysmaplasty