Antonyms for the phrase "more steamed up" can vary depending on the context. For instance, if we take "more steamed up" to mean very angry or agitated, some antonyms could include calm, composed, unflappable, cool, and collected. If we consider "more steamed up" as meaning overheated or overly excited, opposites could include moderate, restrained, temperate, and apathetic. In general, antonyms for "more steamed up" could be words that connote the opposite of intense emotion, agitation, or excitement. Choosing the appropriate antonym would require an understanding of the specific meaning of "more steamed up" in a particular context.