Think of the size difference. An 8+ pound rooster rooster trying to breed a 1 or 2 pound hen can cause significant physical damage including: gashes from toenails and spurs, dislocated hips, fractured pelvises, rips to back of neck from beaks, etc. Just common sense.
The chicks will be small. The constraint is the size of the egg. They will grow to be medium sized chickens laying medium sized eggs. The hens may be mauled, injured, or killed depending upon the size of the rooster.