Antonyms for the expression "trying on for size" could be simple terms like "ignoring," "refusing," "rejecting," or "neglecting." They suggest a lack of interest or an intentional avoidance of testing something out. Additionally, synonyms for ignoring or omitting the process of trying on for size might be "skipping," "bypassing," or "avoiding." These antonyms convey a lack of engagement or disregard for the possible benefits of experimentation. However, avoiding the trial phase can also lead to missing out on potential gains, insights, and experiences. Therefore, even though "trying on for size" can be challenging, it's necessary to grow, learn, and discover new things.