Is the line organization clearly noticeable?

I am posting this question because my jawline is bothering me.

My face is naturally on the rounder side, but lately, the way my jaw muscles on both sides bulge out whenever I clench my molars has gotten much worse. It keeps bothering me because it seems like only my lower face looks wide in photos.

People around me keep recommending that I get jaw Botox, but honestly, since it’s my first time getting an injection in my face, I’m suddenly getting scared that I might lose the strength to chew or that it will look awkward. Still, since they keep recommending it, I kind of want to get it.

Usually, how long does it take after the injection for the muscles to shrink and the face to feel slimmer?

And unlike weight loss, is the body line definition clearly visible?