We all have different set-ups and different coops. If you could post a photo of yours inside and out I may be able to offer specific suggestions.
I have a large on-the-ground coop and my nests are a two to four feet above the coop floor. I let my broody hens decide when to bring the chicks off the nest. Sometimes that is within 24 hours of the first one hatching, sometimes it runs into the third day. They are pretty inconsistent about that. Mine have never had problems getting the chicks to the coop floor.
When it's time I put food and water on the coop floor where the chicks can get to it. I don't know what your current food and water look like but there can be a couple of issues with this. If you put food out in a new container the other adults can consider that a treat, even if it is the same exact food available to them. So they can wipe it out. As these are likely on the coop floor, the other chickens can scratch bedding or trash into it. I set the water on a piece of plywood to keep it away from the bedding and raise it slightly to try to keep it cleaner.
My coop is big enough that I put a 3' x 3' piece of plywood on the bedding, then put this type of waterer on that. The platform around the waterer is big enough the chicks can hop up and stand and I fill the bowl with rocks so the chicks can't fall in and drown.
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Since eating Layer with the excess calcium can possibly harm the chicks, I feed all the chickens the same thing and offer oyster shell on the side. The hens that need the calcium for egg shells seem to know it, the rest do not eat enough to cause harm. If you offer Layer to the hens the chicks will get to it. I've seen broody hens move feed from a high feeder down to the chick's level Within two weeks the chicks are flying up to eat it directly.
My broody hens typically keep the chicks in the coop for a couple of days before they take them outside. That may have something to do with my pop door being raised a bit. Once she takes then outside they stay outside all day everyday. At night she brings them back into my ground-level coop and settles onto the floor somewhere, usually in a protected corner. Mine do not take their chicks to a nest, maybe because there isn't one on the coop floor. If one is available on the coop floor she might use it, she might not.
That pretty much covers it. Provide food and water where the chicks can get to them and leave her alone. One word of warning though. Baby chicks often like to crawl up under the hen's wings or feathers. I once killed a chick by picking the hen up and crushing it under her wing. That's not a good feeling and part of why I say the more I interfere the more harm I do. So if you do pick the broody up, be careful.