Male mannequins have never caught on quite like female mannequins. They come in one basic size with a 38-40" chest, six feet tall. Some have fine muscle definition, others are simple flattened cylinders for bodies with equally dull arms and legs. Faces range from fully painted with facial hair and eyelashes to knobs or balls with no features, to headless mannequins.
Unlike female mannequins, males have not entered the territory of plus sizes. Larger models are rare indeed, despite the fact that most Americans are much larger (if not taller) than the average male mannequin.
Teenage mannequins and petite male mannequins (for displaying vintage military uniforms, for instance) are also quite rare; again the six-foot adult male is by far the prevalent style. Sitting male mannequins are not as common as sitting female mannequins, and other poses (lying down, kneeling, etc.) less common still.
Even so, if you go online to shop, you will find a broad selection of faces, bodies, poses and colors in varying price ranges. Don't despair! The man mannequins are out there. Or you can have one custom-sculpted for less than you may think! Ask this company.