How do some girls get waist like 30+?

what are you talking about? do you mean waist and hips measurements? if so then your hips are wider or more narrow depending on how much estrogen was being produced when you went thru puberty if you produced alot you may have a femine body small waist and more wider hips it is kind of fat acilated but mostly just has to do with genetics and how much estrogen you produced thriught puberty, but even if you wanted to have wider hips you cant get them by talking estrogen pills it doesnt work...