Yup! “Oh, she should probably go down a band size and up a cup size” popped into my head one day and I laughed at the absurdity.
I introduced my wife to the world of proper bra fit, because she’d never known any of it. No one taught her. Made me feel vaguely guilty of mansplaining, but it helped!
Not to point to the other site, but r/ABraThatFits is a great place to start. They have guides and stuff. It’s fascinating.