What can I do slim down my heavy & jowly looking lower face in my mid 20s? (Photo)

Liposuction under local with the addition of Morpheus and Facetite RF would help the face look a lot nicer and more trim. There is minimal downtime and right away you look better.

Surgical contouring is a great way to get a slimmer face/cheeks/chin.There are also several nonsurgical options to consider. Some can be done at the same time. Surgery combined with injections and laser treatments before or after surgery is usually the biggest difference.  For people not interested in surgery, Botox, hyaluronic acid injections and laser treatments are the most reasonable options, maybe combined with a chemical peel.These procedures can be done safely in the office and the results are often very satisfying. An in-office private consultation and examination with a board-certified plastic surgeon would be the best way to fully  address your specific concerns and determine the right treatment plan.I hope this helps answer your question.  If it does, please take a moment to up vote this answer on the “respond” button on the top right.  

Facetite, morpheus, buccal fat pad reduction all help this and threads. see an expert.
With significant neck sagging you would need a neck/face lift with muscle tightening (platysmaplasty). at the same time lasers (fraxel,  co2 or erbium( or microneedling RF (fractora, intensif) can be . performed to improve the crepe skin or wrinkles.  You need a formal consultation, as the neck can be treated with a combination approach:
1. micro needling and lasers for texture
2. botox, disport or xeomin to help platysmal bands
3. intensif or fractora RF microneedling for crepe skin and lifting
4. fillers like belotero, restylane silk, juvederm volbella to improve lines and folds
5. neck/face lifting if sagging is prominent or early starting +/- platysmaplasty (muscle tightening)
6. J plasma/Renuvion, thermiRF, inmode facetite 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 full evaluation and treatment plan based on your individual situation and goals.
Best, Dr. Emer.