I've seen a hen get her chicks out of a ten feet high hay loft. Mama said jump and they did, then ran to her. I regularly have hens hatch in nests about 4' off the coop floor. The broody hens have never had a problem taking their chicks to the coop floor. Don't waste your time worrying about a chick getting hurt if it falls.
Now let's look at the real issues. Thanks for the photo, it helps. I once had a hen hatch in a cat litter bucket about 4 feet above the coop floor. The top of that bucket was 7-1/2" x 11-1/2", too small. Sometimes the first chicks that hatch like to climb up on Mama's back while she is hatching the later chicks. In that nest, when they fell off they missed the nest and fell all the way to the coop floor. Four different times I had to pick a chick up and put it back in the nest with Mama. Probably the same chick most of those times. The chicks that fell four feet were not hurt. I retired that nest after that hatch. Looking at that photo I don't think you will have that issue with that nest.
I don't know how big that coop is. The broody hen and chicks don't take up much room to start with but the chicks grow. Is that coop going to be big enough for all of them when they are adults? The broody should protect them until she weans them. After she weans them they will be on their own to make their way with the flock. That would be my biggest time of concern. The broody will integrate her chicks but they will still have to handle their own pecking order issues as they grow. Tight quarters and pecking order issues can be a risky combination. I'me thinking mainly at night as they settle down and in the morning when they wake up if they are left locked in there for long. This is all down the road but something you might want to think of when planning your next move.
I let my broody hens raise their chicks with the flock. Typically my broody hens take their chicks out first thing in the morning and spend all day outside. But they bring the chicks back into the coop at night, where they spend the night on the coop floor. But my coop is at ground level, yours is elevated. The baby chicks sometimes have problems navigating a ramp at first. The broody hen can go to the top of the ramp and call her chicks. But the chicks don't know to go to the bottom of the ramp and walk up. They often gather right under her on the ground and want to go to her but don't know how to use the ramp. Often she may hop back down and take them to sleep under the ramp, where they might be vulnerable to predators. If you don't isolate them you need to be there at bedtime in case they need your help.
When my main coop is pretty crowded I sometimes move the broody and her chicks to a shelter in my run, a large area protected by electric netting. If I leave her and the chicks locked in that area for two days and two full nights, she takes them back to that predator-proof shelter at night. There are no concerns with ramps or anything else like that. They are safe from predators and get to roam with the flock during the day so she handles integration. That's different from the pecking order.
You can leave that hen and chicks isolated from the flock for as long as you want and handle integration yourself. Both her integration when she weans them and the chicks integration when you are ready for that. Lots of people do it that way. One word of warning if you do try to isolate them, either for a couple of days or for weeks or months. Make sure the chicks cannot escape and get away from Mama's protection. I had a problem with that once. If Mama cannot protect her chicks they are in danger from the other hens. So either let Mama out with them or make sure they stay in with Mama.
If you plan to isolate them, I'd wait until the hen has finished hatching and brought them off the nest. She will know when the hatch is over much better than you will. I've seen broody hens bring their chicks off the nest in less than 24 hours after the first chick hatched. I've had some wait until well into the third day after the first one hatched. There is a warning with this too. I once killed a chick by crushing it when I picked up a broody hen. They sometimes like to crawl under her feathers, especially under her wings. I crushed a chick that was under her wing when I picked her up. You can pick her up, just be careful.