This is a calc to show how proper technique means that it doesn't require Class 1 lifting strength to break a neck.
This article demonstrates how the neck can act as a lever to increase applied force. Your head balanced properly in an upright position only exerts around 12 lbs. of force on your cervical spine. However, tilt your head forward 60 degrees and that force increases to 60 lbs. of force.
A can opener is probably the most simple neck crank. It involves simply going to guard or mount (preventing your opponent's body from shifting) then cranking your opponent's head forward/down in a case of hyperflexion - similar to dropping your head forward when you have bad posture, but with a hell of a lot more force.
Your cervical spine is a class 2 lever when locked forward, as the load is between the effort and fulcrum. The effort (blue arrow) is at the top of the cervical spine/the back of your head. The fulcrum (red dot) would be the part of the cervical spine that allows motion, your intravertebral disks. The load (blue square) would be the frontal area of the cervical vertebrae being compressed.
By our definition a Peak Human has to lift at least 500 lbs; according to StrengthLevel, a 170 lb. elite powerlifter can deadlift 502 lbs. That same powerlifter can perform a bent over row of around 299 lbs.
The bent over row uses the pretty much same muscles a can opener uses during full compression, so it provides a decent estimate of the maximum force they can apply.
I did my calculation based on the average length of a neck (3.9-4.7 inches) and the estimated diameter of a cervical vertebrae (I tried searching up the average but I could only find the average for the spinal cord/inner part of the cervical vertebrae).
The average neck circumference is around 15 in. meaning that a neck (which is more ovular in shape) will have a thickness around 4 in. The largest vertebra seems to be around half the size of the neck so we can give it a front-back thickness of around 2 in. The pivot point is would be your intervertebral disk, so the distance of the load from the pivot is around half of the front-back thickness. We know the distance both the effort and load from the pivot so we can calculate mechical advantage.
4.7 in. / 1 in. = 4.7 (Supported by the article which shows an increase of around 5x the force on the spine with bad posture)
Then we can find the amount of force our theoretical bare minimum peak human can apply.
~300 lbf * 4.7 = 1410 lbf. (~639 kgf)
That's 200-400 lbf more than the accepted value (1000-1200 lbf) for snapping a human neck.
So yes, in an ideal scenario with no resistance, a peak human can break a neck even with a comparatively weaker neck crank.