You can try luring them in near dusk with meal worms or scratch and close the door behind them. Just until they're trained. Meal worms are high in fat and scratch is low in nutrients. Both usually make chickens go wild for them. So I wouldn't do a whole bunch and on an ever lasting basis. But for training, sure why not. Keep it to less than 10% of their total daily ration.
You could also try raising the roost in your coop a little higher.
I've always trained my birds from young. It usually takes corralling them for a few days (no treats) to where I want them to be and they seem to get the message and rather go up on their own than messing around with me.
Anybody who didn't follow the treats into the coop... I would get them once they are roosted and take them to the roost where I want them. Chicken are creatures of habit. Once you get trained to a new habit, it *SHOULD* stick.
If you've never "homed" them to the coop, locking them in for a few days to a week could help.
A coop seems much safer than being in the open. And an effort that will probably be well worth the time you spend training them to it.
Good luck!