From the picture, it looks like your face shape looks nice and is relatively V-shaped already. If you are looking to make your face slimmer, the only additional treatment you need would be to reduce your cheek/buccal fat a little, which is slightly bigger on the left cheek. A good treatment to consider for that will be buccal fat radiolysis.
With regards to treatment options to achieve a slimmer face, it will depend on the bone structure, skin quality, gender and facial proportions of the person. The following are some of the common treatment options that can be done to improve the contours of the face and make the face look slimmer.
1. Botulinum toxin injection to the masseters to reduce its bulk, which will in turn make the lower face slimmer
2. Energy devices like Thermage, HIFU and Ulthera can help to firm and lift up saggy skin over the lower face to make the face slimmer
3. Dermalift or intradermal microbotox injections can also help to tighten and lift saggy skin over the lower face and improve the facial contours
4. Radiolysis with radiofrequency microneedles to help reduce buccal/cheek fat volume
5. Filler injections at the right places can help with replenishing volume deficits, lifting and improving overall face contour
6. Threadlift will improve sagging over the lower face/jowling and make the lower face look slimmer
Often, a combination approach is used to achieve the best results. Do get an assessment by a certified and experienced doctor who will be able to discuss the treatment options available with you and come up with a customised treatment plan for you.