Is this the DAO muscle and am I a good candidate to get Botox in this area?

botox can help mildly but you need skin tightehing, threads, fillers, even chin augmentation to help this area. this is early sagging what we call the marionette area.
Nasolabial/marionette folds -- Fillers (juvederm, radiesse, restylane, belotero), sculptra, lasers, microneedling/prp, ultherapy, threads

at home peels like cosmelan, enlighten and aerify along with dermarolling (EmerageSkin roller with anteage AERIFY MD ampules weekly, see link) should be started now to prevent further aging.

For facial rejuvenation, I would suggest a combination approach of
1) skin care with products and PRP/microneedling
2) PDT light therapy few times a month with growth factors
3) laser treatments like clear and brilliant regularly and a few times a year Fraxel/halo Viva, Co2/Erbium
4) Sculptra injections a few times a year for collagen production with fillers like juvederm/restylane/belotero/radiesse/bellafill
5) thermage/ultherapy for yearly skin tightening with or without PDO or cone based instalift threads for lifting
6) botox every 2-3 months to stop movement lines and prevent lines at rest
7) deep microneedling RF like Fractora/morpheus8 for tightening of the skin
8) Vascular laser like vbeam/excel V or BBL forever young treatment every quarter (3-4 months)

Best, Dr. Emer.

Thank you for your question. This area is not the DAO muscle. Botox can be used to help the area which would depend on the amount of laxity of your skin. In this area we can use items such as Bellafill to enhance the collagen in the area due to the downward turn of the lips and sagging in the area. I recommend you consult a physician who is experienced with procedure to help in eliminating these types of issues.