Jawzrsize Before and After – Do Jawline Exercises Work? Eric West Review

Answer is right there at the top of the comments.

Commenter: "Anyone else having a hard time finding peer-reviewed scholarly articles saying that this is a safe and effective method?"

Video creator replied: "It’s simply a piece of exercise equipment and does not warrant medical studies like some type of a pharmaceutical drug"

The answer is no. In all likelihood it does not work. Also the video thumbnail clearly uses different camera setups for the before/after, and the difference could be due entirely to perspective. Not to mention photoshop editing etc.

As well as there being no scientific evidence, I also doubt if there's any proposed mechanism by which this would work. Without mechanism or evidence, it's 99% chance quackery.