We have a 4'x8' raised coop. We have gable vents, a roof ridge vent, two windows and a pop door. The windows and pop door are always open as the covered run prevents rain and snow from getting in the coop. We use a snow rake to clear the ridge vent. But I would like to add more ventilation.
Much depends on the climate/weather you have to deal with. But you always need so much ventilation that the air doesn’t get damp. Avoid a smelly and unhealthy coop.
I have the whole south side open with hwc. With a large roof against rain coming in,
But I live in a mild climate. In cold winter weather (many states in US and Canada ) this might not be a good solution.