For me it's a tough call. In my experience it is too much comb for a pullet at that age and too little for a cockerel.
Leaning closer to a cockerel because of size. Gonna say cockerel because of amount of color at that age.
Keep us posted this one will be interesting.
Are you sure it's a leghorn?
At 5 1/2 weeks my males usually have much bigger combs and females have tiny combs with no color yet.
It looks like what I'd expect to see from a cockerel of a smaller comb breed.