Antonyms for "most scaled-down" include "largest," "biggest," "most significant," and "most extensive." These terms denote size or scope, which are opposite in meaning to "scaled-down." Other antonyms could be "most grandiose," "most sprawling," "most inflated," and "most maximum." These words emphasize the magnitude of something, in contrast to the reduced or minimalist character of "scaled-down." In terms of scale, these antonyms represent what is at the other end of the spectrum from "most scaled-down." Depending on the context, these antonyms could highlight a different aspect or quality of something, such as its grandiosity, complexity, or impact.