Is it true that applying botox in the masseter makes your cheek muscles (maybe other muscles as well) stand out?

Actually, injecting Botox into the masseter helps narrow the jawline, which may make your cheeks stand out more. But it won't really help if you don't have hypertrophic masseters. The optimal treatment for cheek bone enhancement is filler. I'm unsure of why you want to avoid filler. Filler will actually last longer and give you better results and will ultimately be less expensive than Botox in the long run. I recommend you consult with a well trained injector such as a Board Certified Dermatologist or Plastic Surgeon to find out what the best treatment is for you.

Injection of Botox into the Masseter can, over time, cause some atrophy of the muscle. When the muscle is hypertrophic (the reason for injecting it with Botox) and it atrophies, the cheekbone can appear to be more prominent. Make sure you see an expert in use of Botox.