Stiffness when pedaling

[kiddo]

I just bought a child's bike for my 2 yo but the pedals are too stiff for him to pedal. Any suggestions as to how i free these up that he can pedal without me having to push him? The bike pedals fairly freely when the wheels are off the ground, however when the back wheel is in contact with the ground it is very stiff to pedal.

[TESTUser111]

Hmm, strange that it pedals freely when off the ground. Are you able to upload some photos? If we can see the type of bike/components it will be easier to guess what the problem could be...