Hi, I'm really interested making a realistic characters, but I don't really like a sculpting from a low-poly mesh, I'm more comfortable making a whole character from a sphere.
is there are a different course of making a realistic characters with a different workflow?
Whether you start from a sphere or from a lo-poly basemesh, either way you should arrive at the same starting point of this course. Which is beginning to form general anatomy before refining that anatomy.
We don't recommend starting from a sphere because it's not efficient. You can certainly choose to start from a sphere but it's not our recommendation. The other approach we teach is starting with a skin modifier (which is similar in concept to Zbrush zpheres).