I'm not really much of a character modeller, but am aware that excellent results are possible starting with either a cube or a sphere.
I've tried both, and most of my finished, usable characters used a sphere for the head and a cube for the body.
(human characters anyway).
Then theres the 'joan of arc' modelling tut, which i found super helpfull. (still a cube though)
https://3dtotal.com/tutorials/t/joan-arc-modeling-the-body-michel-roger-character-arc Worth a look if you haven't seen it yet.
In regards to your donald trump, although the model itself has some 'pinched' areas, its amazing how the right texturing/coloring can show who it is.
I picked him straight away as donald trump, but mostly the coloring that makes him so recognizable.
Good stuff olan.