Loom large is an idiomatic expression that refers to the way something or someone appears to be imposing or significant. If you're looking for synonyms for this phrase, you might consider using words with similar meanings, such as: "dominate," "overshadow," "tower over", "take center stage," "loom ominously," "cast a shadow," "command attention," or "be of great consequence." Each of these can be used to convey the idea of something or someone having a significant impact or presence, and they can be used interchangeably with loom large in a variety of contexts, from professional settings to personal relationships.