3D model / sketch


I was trying to 3D out of this cartoon sumo here {Attachment}… But after so many attempts, I am not getting desirable results. I have used blender 1st time, Then tried zbrush . I am new in zbrush so no results.
anyone there could help me shape the base of this model?

Like fat chin and fat neck and back of the head… :sweat:

Please need help… I only have this image, no side view or back