Try to create mind-muscle connections to face muscles. While stoned I've had good luck finding these connections (to glutes, hip flexors, abs, etc years ago when I had to fix my posture). In the past I had to turn my head upside-down or massage my face. It's a nice sensation, like a milder version of any other activity that feels relieving. For me at least it feels like the inside of the roof of my mouth or the stuff right behind my nostrils is being pulled back into my skull and all the pressure equalizes. Sometimes pushing these muscles upward or outward is required for me but I don't usually have to focus on it after making them manual adjustment. I confirmed my face is not changing in the mirror, and when I do engage external facial muscles it's less effective.