It is hard to do a perspective. Growing up way out in the middle of not much many decades ago, my parents never locked up their chickens. They totally free ranged and the coop door was not closed at night. Some chickens slept in trees. even in winter. We hardly ever lost a chicken, but I do remember a fox and a dog getting shot.
Living here, I lock them up every night. I've dispatched skunks, possums, and raccoons here and we have coyotes howling pretty close some nights so I think I would have lost some if they were not locked up. I was losing maybe two chickens every three years during the day with them free ranging, I think to a fox but I've never been able to prove what it was. When I lose one like that, I leave them locked up for a month or so in order for the fox to not learn there is an easy meal here.
Then twice in the past six months, somebody abandoned some dogs in this area for the good life. I'm in the country here, by the way. Both times I was away from the house when they hit. I lost 8 chickens one time and 5 the other. For me, that is a lot.
I've never lost one when they were locked in the coop or run.
What you will experience depends partly on what is in your area your area but it also depends on how you manage your chickens. For me, locking them up at night worked real well for a long time.
Part of how you manage them depends on how hard a loss would hit you. For many people on this forum, their chickens are their pets. Even the loss of one is a real big deal, similar to losing a pet dog or cat. I don't like to lose any, but I'm willing to suffer an occasional loss if I can let them free range.