Is it okay to get jaw Botox and contouring injections together?

Lately, the lower part of my face seems to look bigger than before, so I am looking into cosmetic procedures. My jaw muscles tend to protrude significantly, especially when I clench my teeth, so I am initially considering square jaw Botox. However, since I also have some fat on my cheeks, I am not sure if Botox alone will give me the look I want.

So, I am thinking of getting square jaw Botox and contouring injections together, and I am wondering if it is okay to do both at once. I would like to know if they are administered to different areas, or if doing them together could cause excessive facial swelling or bruising.

Also, I heard that square jaw Botox is more effective when the muscles are well-developed. When I checked at home, the sides of my jaw tend to bulge out firmly when I clench my teeth. Given this, I am wondering if it is worth getting a consultation for Botox.

Since this is my first time, I'm looking for just a slight slimming effect on my face rather than a dramatic change. For those who have received square jaw Botox, I'm curious how much you initially received and how long it took for the effects to show. If you've had any other procedures done at the same time, please recommend those as well!