The phrase "are big" can be a bit limiting in language usage. A few synonyms for this phrase include "are large," "are immense," "are colossal," "are huge," and "are gigantic." However, if you're looking to spice up your language even further, there are plenty of creative alternatives. For example, you might use "are substantial," "are grandiose," "are monumental," "are towering," or "are mammoth." These words can help add more emphasis and power to your descriptions of size and scale, and make your writing sound more polished and sophisticated.