The phrase "soaring up" implies a sense of upward motion, ascent, or growth. Its antonyms, therefore, would involve words that suggest the opposite: descent, decline, or shrinking. Some possible antonyms for "soaring up" might include "plummeting down," "dipping," "falling," "dropping," "declining," "sinking," "shrinking," or "contracting." Depending on the context, other antonyms might be appropriate as well, such as "stagnating," "plateauing," or "leveling off." By using these antonyms, writers and speakers can create a contrast with the idea of soaring up, highlighting the opposite meaning and creating a more nuanced and effective message.