Leghorns should have yellow soles on their feet. I am pretty sure she is not a Leghorn.
Breed with black feathers and white soles on their feet include:
Black Australorp
Black Minorca
Black Andalusian (these happen when people breed Blue Andalusians)
All three of those have single combs, but I think the chicken in your picture has a pea comb. So she would have to be something else, probably an Easter Egger as several other people have suggested.
If she has a pea comb, she must have at least one parent with a pea comb.
Leghorns and Australorps have single combs, or Leghorns occasionally have rose combs. There is no possible way to combine those comb types and get a pea comb.
So to get a pullet with a pea comb, at least one other kind of chicken must be involved. I would guess there is some Ameraucana or Araucana mixed in, maybe several generations back rather than her being a direct first-generation cross.
I thought Leghorn earlobes were not particularly noteworthy until they get a bit older than the pullet in the photos, so I'm not ready to completely rule out some Leghorn influence. I agree that she cannot be a pure Leghorn.