I have a 60 ft L x 20 ft W chain link fence for the chickens. I strung bird netting over the top of mine to keep hawks out and the chickens in. I don't count on it to keep predators out (other than hawks) and a huge snowfall could probably take it down (but we don't get that much snow here). I'm really happy with mine, no escapees, and it hasn't fallen or been breached. It's lasted about a year and a half so far.
i keep mine locked in the coop while at work .. they have to be on a timed program so they cooperate .. you can use food, got to get them just hungry enough, and the coop has to be comfortable or they wont want to go in ..
Without some sort of a top on it they will easily pop over the fence.
While netting can and will be brought down by snow, leaves, branches and wandering critters it may be the best option short term.
Sinking 4x4's in the ground and putting short pieces of 2x4 (4') on top will allow the netting to stay tall enough you can walk in there. A frame at the gate would be needed to keep it raised up.
There are a lot of kinds of netting you will want a stronger one than is available at Home Depot....
I don't know the pens original use it was here when I got the house. The chain-link fence is about 5 feet high and has been extended to about 9 feet for most of it's run. My buddy thinks it may have had chickens in it before due to how much the fence along the ground has been secured with a short stone wall to keep things from digging under the fence. It's maybe 30’ by 20’ in area so like 600 Square feet the coup is a small prefab thing that came with the birds my buddy need to downsize and I think he needed a bit of cash don't tell him he's a proud guy and would never say. I have a Polish Black Rooster a Saphire Gem Rooster/chicken gone to rooster I do t really know how that works but I know he's nosey enough to piss off my neighbor two polish hens( that have yet to lay an egg) and there Rhode Island Reds my egg playing queens. But man do they like to escape. When I'm home they like to hang out, but when I go to work it's on and the great escape begins.