the muscle maps are textures...they will only look like what you see in the promo images...they do not deform the mesh.

The morphs, the lower link yo provided, will change the actual muscles/shape of the model...that's what you need...

EXCEPT THE FACT YOU ARE A GREAT ARTIST ALREADY....yo can use what you already have, at least in still images. Poser, which came before DAZ Studio was meant as a 2D artists model./form, to manipulate in a 2D program...you can add shape to the legs , arms, etc...shadow  and so forth to achieve what you need rather than in the actual model.

But I realize you now want to do it in 3D....so get the morphs. You can also manipulate the mesh itself without the morphs...at least in Poser...I don;t use DAZ Studio, so not sure how much you can change the figure in there....see if there are magnets or morphing tools within DAZ Studio.

Humankind has not woven the web of life. We are but one thread within it.
Whatever we do to the web, we do to ourselves. All things are bound together.
All things connect......Chief Seattle, 1854