That’s the “secret” to that pose - your arms should be/look larger than your head.
And even with enormous arms, it’s often the guys with smaller heads who tend to have better success with this pose.
I’ve seen some guys “cheat” on the pose by tilting their heads back a bit to reduce its perceived surface area/size, thus creating the illusion of larger arms by comparison.
Of course, hiding your head diminishes some of the impact.