A client recently asked me what I recommend for the 'waddle' - the sagging of the skin under the chin. Products that help firm and tone are Beautycounter's Countertime tripeptide radiance serum and tetrapeptide supreme cream. For these products (or any products) to give you results, you must use them consistently. Massage the serum and cream down your neck every single night.
For additional help, look into Gua Sha. You can watch my FAVORITE professional clean beauty makeup artist demonstrate on my Clean and Bright with Becky Facebook page from April 23, 2020. Just search the posts for gua sha. Here is that link: Clean and Bright with Becky on Facebook
Purchase the gua sha from Herbivore Botanicals here: https://www.herbivorebotanicals.com/products/rose-quartz-gua-sha?_pos=1&_sid=9d55eef10&_ss=r&variant=8127864275062