Oh good! I have seen so many pre-fab coops that state they will hold 6, and truthfully should not hold more than 2, unless they are bantam chickens, and only 3-4 of those.
Ventilation and space are a big concern with chickens. If your chickens get a long then you have enough space. If they start fighting, eating feathers, attacking each other, then you don't have enough space. Some birds can tolerate a bit of overcrowding, some birds cannot. Always solve for peace in the flock.
5 birds should have at least 20 square feet in the coop, and 50 square feet in the fun. That is a general rule of thumb to go by for full size adult hens. Roosters take more room than hens. So often what seems to be more than enough room for chicks, rapidly becomes not enough room for adult birds.
Mrs K