You're right that some breeds like Polish and silkies can come bearded or nonbearded, but there is no way to choose which because they are not sorted that way.
The same goes for ordering "blue" breeds. As you can see in the descriptions, blues usually come in a mix of blue, black and splash. When that's the case, you cannot choose which you receive.
Similarly, you can't choose what color Easter Egger you get, or which birds come in a hatchery or breeder choice assortment. All your buying options are always right on the pages.