There are several synonyms for the phrase "is control of," including "holds sway over," "dominates," "governs," "commands," "mastery over," and "regulation." Each of these phrases implies a level of power or authority over a particular situation or object. For example, if a person were said to have "mastery over" a skill or subject, it would indicate that they possess a level of expertise and have achieved a high degree of control over the subject matter. Similarly, if a country were said to "govern" a particular region, it would imply that they hold a level of control and authority over that area.