As someone with terrible genetics for arms, I went into my training with the idea to emphasise triceps, but I generally eschewed exercises like CGBP due to never having a training partner in favour of pushdown variants and skullcrushers. I eventually started doing behind the neck db extension to get a real good stretch, but the lateral head of my tris is far more developed than the long head - and the long head is what you need to have thicker looking arms from the sides.