What play fights?
There are no play fights with chickens. Every single fight is serious. When you are a chicken with a complex social hierarchy that makes your flockmates wants to beat you up, and you have hundreds of predators out there that could attach at any moment, you need to conserve your energy. There is no reason for play fighting when you are in that situation. People say they see their chicks play fighting, but if you notice, when they ram into each other's chests they actually hurt each other, because they fall and scream, and most of the time slash each other with their claws in the process. When a chick runs up to another and bites them on the head, neck, or anywhere else for that matter, they are certainly not playing either. I have hatched many eggs before, and the chicks come out ready to beat each other up. When one chick hatches, rests up for a few minutes, and sees another chick out of the egg, it makes its way to the chick, half-crawling and half-walking, and starts pecking its opponent forcefully.
Chicken life is brutal. Every ounce of energy needs to be conserved for life-or-death situations, which happen every day, all throughout the day. If you are weak, you get killed. It is as simple as that. There is no room for play fights in the chicken world.