I would probably go with an Austrolorp if I had to pick.
I am new to chicks and ordered a variety including, Red Stars, Barred Rocks, Black Austrolorps, Buff Orpingtons, Silver Laced Wyandottes, Araucanas, White Rocks, Delawares and of course my free rare chick.
I know for sure a few I can rule out
But that's as good as it gets for me knowing what breed she is. She looks like a penquin to me