Can I get deep cleft chin and how? Without surgery

Your pictures are not very good to evaluate your concerns. But chin implant does not seem to be a necessary option. The angle of your neck indeed could be improved but you should have a hands on consultation with a PS.

Dear Crackpot,Thanks for your pictures.  Typically mentalis muscle strain is due to several factors: (1) retrusive lower jaw, (2) excessive height of upper jaw and (3) possibly a retrusive chin.  A sliding genioplasty does not improve mentalis muscle strain.  You can have some BOTOX® in the area...

I believe there is nothing wrong with your forehead. Your upper/lower jaw did not grow forward as much as it should have. You would need braces and jaw surgery to correct the disharmony