Oh goodness that little baby is way too young to determine for sure! She hasn't even feathered out into her adult feathers yet! Her coloring will probably change quite a bit before she reaches maturity.
Side note: I have two brooder boxes full of 3-week-old chicks who look just like that.
The parents are Easter Egger hens, and a RIR rooster.
Some are skittish and shy, some will literally fly right up onto your shoulder they are so friendly.
I currently have 2 EEs, 2 RIRs, 2 Plymouth rocks, and one light brown leghorn (supposedly). They're roughly 3 weeks. Maybe. Not sure of their exact ages but I'm in love.
My plymouths and one of my EEs are SO friendly they literally just want to sit on my shoulder and poop on me all day.
Will be interesting to see the final end product of what the light brown leghorn will turn into.