Would filler to my cheeks lift my saggy skin even if it's due to loose facial muscles?

You have a few options and since you are young you probably do not need much. I like to use Voluma for the cheeks to bring back lost volume to the area. Starting with 1 syringe for each side and adding overtime if necessary until you achieve the look you are going after. Ultherapy is also a nice treatment for skin tightening. Using both HA fillers and Ultherapy in conjunction with one another can give a nice result.

"I suggest reaching out to an expert for a formal consultation. I like to recommend my patients start a combination of facial rejuvenation treatments.

1) Skincare with products and microneedling/PRP
2) PDT Light Therapy a few times per month with growth factors
3) Laser treatments like Clear + Brilliant regularly and others (Fraxel, Moxi, Viva, CO2, Erbium, Halo) a few times per year
4) Sculptra injections a few times per year for collagen production with fillers like Juvederm, Restylane, Belotero, Radiesse, and/or Bellafill
5) Thermage/Ultherapy for yearly skin tightening with or without PDO or cone-based Instalift threads for lifting
6) Botox every 2 to 3 months to stop movement lines and prevent lines at rest

Best, Dr. Emer."

The good news is that you're a little young for much laxity of the underlying SMAS structure.  A great combination for your would be the Vampire Facelift which strategically places HA filler as well as your own platelet rich plasma into your skin and deeper tissues to both 'lift' your skin and stimulate your stem cells to replicate and improve the integrity, quality of your skin.  The PRP will also stimulate the development of new collagen, elastin and vessels to enhance your glow, texture, smoothness, tightness and dewynes!Give it a try!  I love it!In good health,Ellen Mahony, MD