Does Macy's size the watch bands?

Macy's sell their watches as-is from the watchmaker without modification. If you bought the watch through Macy's and if the watch has a metal bracelet instead of a leather or fabric watchband, then they will be able to resize it for you on the spot (if the location you go to does have a watch repair center). Otherwise, I am quite sure they'll refer you to other locations that might have such a service, or last-case scenario, send it in.