Well...
She isn't a Welsummer (not pencilled, no salmon chest)
She isn't a Barnevelder (she's laced, but not double laced on dark brown with black)
...and yes I think she is a she.
However, she may be a Penedesenca (oh how I hate trying to remember how to spell that name)...Meyer carries those, and that would place her in rainbow as Penedesencas lay dark brown eggs.
Look at the top photo on Meyer hatchery Penedesenca below...that Penedesenca hen has the wrong leg color but a similar partridge lace pattern, then look at their photo on the bottom adult hen, pencilling but yellow leg color. Obviously their line has some differences (or they've put in a wrong photo). She looks like she may have gotten the laced look with yellow legs from their Penedesenca line? (That's assuming she is from the "rare" package)
https://www.meyerhatchery.com/productinfo.a5w?prodID=PAPS
...but her comb doesn't look full enough (granted she is still younger)...and it should start single and then split to a crown...
Another possibility then is their Partridge Rock, which I thought of at first looking at her. She could also be included in their rainbow package as their photo for that indicates simply a layer assortment.
https://www.meyerhatchery.com/productinfo.a5w?prodID=PARS (Partridge Rock)
https://www.meyerhatchery.com/productinfo.a5w?prodID=APRS (Rainbow Layer Pack)
I looked at their rare package, and the only one that is barred and has gold is the Golden Cuckoo Marans, but she doesn't look anything like that to me:
https://www.meyerhatchery.com/productinfo.a5w?prodID=GCMS
My best guess? I think Partridge Rock.
LofMc