Overlargeness is a term that may be hard to find synonyms for, as it is quite specific in meaning. However, some possibilities include "oversize," "overabundance," "excessiveness," "grandiosity," "bigness," "magnitude," "massiveness," and "immensity." These words all suggest something that is bigger than what might be expected or necessary, and may connote a sense of extravagance or overwhelmingness. Whether describing physical objects or abstract concepts, these synonyms can help to convey a sense of enormity and emphasize the sheer size or scale of something.