Mid and lower face sagging - what is the best treatment to reverse this? (photos)

I've included 2 pictures - the one with pale background is standing and one with brown background is lying down. I'm wanting to address the lower face "heaviness" and beginning of jowls. I'm in my mid 30's but I see it's beginning to give me a square face which I do not like. I've always had a square face but have had Botox to the massager which has helped. What is the best treatment for me to reverse and hopefully prevent or mitigate future jowls and sagging?