The opposite of "more mismatched" is "more matched." It means that the items or people in question are better suited for each other, and there is no apparent discordance. The opposite of "more mismatched" could also be described as "harmonious" or "compatible." These antonyms signify a sense of cooperation and agreement between the elements, whether they be clothing items, colors, or people's personalities. Other antonyms such as "balanced," "coordinated," or "synchronized" all imply a sense of unity and similarity. If you're looking to avoid mismatched elements, strive for a more cohesive look or harmonious relationships with others.