I want a slimmer jawline. Who is recommended for square jaw Botox?

My lower face is a bit wide, so I've always been self-conscious about it. Whenever I take photos, only my jaw looks round, so I was looking for ways to slim it down, and everyone highly recommends Botox! However, I heard it only works on muscular jaws. Could someone like me, who is unsure if it's fat or muscle, still get a V-line with Botox? Please let me know if there is a specific type of jaw that is recommended for 확실 results, or if getting it on yields the most dramatic results! I really want a sharp jawline.