Kids bikes are getting better but crank length still too long in most cases. 140mm cranks are more appropriate for the height range that Trek’s aimed at.
Youngest a11y starting riding a 24″-wheeled Vitus from around 130cm (now 141cm). Spec its way better than the Trek, cheaper to buy too: 140mm cranks, hydraulic brakes which work, decent Schwalbe tyres, a half-decent suspension fork, and 1×8. Only change I made was a 11-40t cassette to increase the gear range. Slacker 67deg HA, whole bike very confidence-inspiring. Weighed at 12.0kg with pedals and a fatter 2.35″ Smart Sam on the front, so only 400g heavier than the Trek despite suspension fork.
I’ve got a Vitus Nucleus 26 stashed away for when she’s ready for it. Frustratingly that’s specced with 165mm cranks… same length cranks I use at 188cm on my XL Geometron! I’ll be looking for a set of 152mm cranks for it.