Will getting jaw Botox change my facial contours?

I am worried that my face looks big because my jaw muscles are developed.
I am wondering if getting jaw Botox will naturally refine the jawline.
I would also like to know when you usually started feeling the effects.
I am curious if you felt your chewing power weaken after being hit for the first time.
Please let me know if you have experience with how long it lasts.
Please share your satisfaction with jaw Botox and how to care for it.