Have a coop that's well ventilated, not damp, but no direct wind blowing over the roosting birds.
Some people apply vasoline to the comb and wattles; worth trying.
Some minor frostbite will probably happen, and he will manage.
Heating the coop is not a good long-term solution, and can be a disaster, if there's a fire, or during a cold spell during a power outage.
I solved the problem by switching to roosters with small combs and wattles, like my avatar.
Another tip is wide perches, allowing the bird to have their feet spread out on top of the perch. This way they can get their feathers over their toes. With thin perches, their toes wrap all the way around the perch and can stick out at the bottom, where they can't get their feathers over their toes. A wide perch lets them keep their toes warm at night.
I use 2x4s flat side up...Vents well above the Roosts because moisture rises...I run a heat lamp that is connected 3xs so no chance of it falling...Never too warm in my coop..But is not -25C like it can get here...
Vaseline is good on combs and wattles but will still freeze depending on how cold it actually gets...
When I first started chicken keeping, I closed my coop up tight in the winter and had a heat lamp in there. There would be frost on the walls, the bedding was always damp, and by spring they would have respiratory problems and frostbite. Fortunately we never lost electricity those first years or they likely would have frozen to death. By having them locked up with heat all winter, I didn't give them a chance to naturally acclimate to the weather.
Depending on your climate, your rooster may get frostbite on his large comb no matter what you do. It happens and he'll be fine. I've had severa "winter dubbed" roosters that had no issues afterward. I have also moved on to roosters with smaller combs and wattles to avoid that problem.