hold sway
• have great power or influence over a particular person, place, or domain.
• "they had held sway in France for a quarter of a century"
Similar:
hold power,
wield power,
exercise power,
rule,
be most powerful,
be in power,
be in control,
predominate,
have the ascendancy,
have the greatest influence,
have the upper hand,
have the edge,
have/hold the whip hand,
run the show,
be in the driving seat,
be in the saddle,