Would chin filler be a good fix for my double chin? (Photos)

If you seek an improved profile view you could slightly augment the chin with filler or consider options to remove fat in the submental area (which is the area underneath the chin). Classically in the profile view the upper lip should project 2mm in front of the lower lip, which should be 2mm in front of the chin.  You have a slight chin deficiency to which you could consider either a small implant or filler such as Voluma. I think the more dramatic effect would be to sculpt the submental area with targeted fat removal. This could be accomplished by either a liposuction procedure or Kybella treatment.

"For a double chin, InMode FaceTite with VASERlipo would give you the best result.

With significant neck sagging you would need a facelift / neck lift with muscle tightening (platysmaplasty). At the same time, I would recommend lasers (Fraxel, CO2, Halo, or Erbium) and microneedling RF (Fractora, Morpheus8, PiXel8, Intensif) to improve the crepey skin and wrinkles. Overall, the neck can be treated with a combination approach:

1. Microneedling and laser treatments for texture
2. Botox, Dysport, Xeomin or Jeuveau to help platysmal bands
3. Intensif, Fractora, PiXel8, or Morpheus8 microneedling RF for crepey skin and lifting
4. Injectable fillers like Belotero, Restylane Silk, Versa, and Juvederm Volbella to improve lines and folds
5. Face/neck lifting if sagging is prominent or premature, with or without platysmaplasty (muscle tightening)
6. Renuvion (J-Plasma), ThermiRF, and InMode FaceTite/AccuTite for internal tightening
7. Ultherapy and Thermage for external tightening
8. Regular Venus Legacy, Exilis Ultra, or InMode Forma treatments with facials to maintain tightness
9. PDO NovaThreads or Silhouette InstaLift cone threads for lifting and long-term collagen production

See an expert for a formal evaluation and to develop a personalized treatment plan based on your individual situation and goals. Best, Dr. Emer"

A long acting chin filler such as Voluma would definitely help your profile. At a later date you may even elect to have a chin implant, which is permanent.
A liposuction of your submental area of your neck would also be indicated, and this can be done under local anesthesia at the same time. This is a minor procedure requiring minimal recovery, such as a weekend. 
The area that is liposuctioned will look better then it does now at a week postoperatively, but the swelling will continue to subside for several months. 
The combination of the chin filler and liposuction would change your profile appearance dramatically.
Thank you for your question and photographs, and best of luck to you.