This is a boy. Do yours have feathering like this?
Looks like a premature pullet to me.
The feather pattern should be much different if it was a male, here a picture of a 13 weeks old cockerel for comparison https://www.backyardchickens.com/threads/slw-cockerel-or-pullet.922716/post-14275805
And welcome to BYC
That's just what I was going to ask. Male SLW's have a distinctive color pattern with white on the wing bows, which ought to be visible at that age (though last year I had what turned out to be a pullet whose apparent white wing bows were just bad lacing).