Well its hard to say if they are pure and not hatchery birds you could get bigger Leghorn kind of bird and or smaller RIR kind of bird.
Much like a Perduction Red..... If they are hatchery chicks its had to tell..
The Rhoad Island Red chicken has Leghorn in it along with Red Malay and a Asiatic native stock.
i have someabout 3 to 4 weeks old some have more brown leghorn markings on their feather than the others and all are red and redish brown color. i just wanted red color leghorns that was not wild as the leghorn roo i have. he is like racecar fast when you try to catch him. i rir are not as bad to run.