Things that are bigger than usual are oversized, like the oversized luggage that won't fit in the airplane's overhead compartment.
Maybe you prefer oversized clothes, like large sweatshirts that hang halfway down to your knees and have voluminous sleeves that need to be rolled up. Or you may be a fan of oversized desserts, such as gigantic, 12-layer cakes covered in heaps of icing. Anything oversized is noticeably bigger than the standard size. This adjective comes from a now-uncommon 17th-century verb, oversize, "make too large."