Not of that specific cross, but buff on black can give you some really strange effects as they feather out. Let me go look.
Look at post #1710 in this thread. That pullet is a BO roo over a Barred Rock hen but the basic genetics could be very similar.
There is no guarantee you will get a hen that looks like this. In theory the chicks should be solid black but as you can see, that doesn’t always happen. With the down color I’m seeing in yours I don’t think it will. You could get a chicken with yellow or orange somewhat similar to the one in that photo. You could get one with yellow or orange blotches, big blotches even, on black. You could get something totally different. I think it could be exciting to see them feather out.
I’m seeing two different shades of down on those yellow chicks. I don’t want to get your hopes up too much because white leghorn hens are really inconsistent in this but there is a chance the really yellow chicks are male and the ones with reddish are female, basically red sex links. Most of the time with white leghorn hens that won’t happen but you may have gotten lucky. No guarantees.