She is still a hen, but crowing. It's just a behavior that some hens may do to take over the role of a rooster. Like becoming the alpha or dominant hen. I read that it can also be caused by hormonal changes. It doesn't automatically make her a rooster, however.
Hello and welcome to BYC! enjoy your new babies! I love black sexlinks. I have a 6-year old and a chick that are both black sexlinks. And they are both sweet. 🥰