The phrase "is in command" refers to someone who is leading a group or situation with authority. There are various synonyms for this phrase, including "is in charge," "is in control," "has the reins," "is at the helm," "exercises leadership," "holds sway," "is the head," "is the boss," "calls the shots," and "is the master." All of these synonyms imply a level of power and responsibility over a group or situation, and can be used interchangeably depending on the context. Whether in a professional setting or personal life, being in command involves taking charge and making important decisions, and having a selection of synonyms to choose from can help add variety and nuance to communication.