The civilization with the most Envoy6 Envoys on a city-state, and at least 3 Envoy6 Envoys, is considered that city-state's Suzerain. There can be at most one Suzerain; ties are not allowed. If nobody has Envoy6 Envoys on a city-state, there is no Suzerain. The Suzerain gets several significant benefits, which are described below.

Unique city-state bonus: This is a powerful bonus which no other city-state will provide. For example, Jerusalem acts as a second Holy City for your religion, meaning that Jerusalem will exert religious pressure on nearby cities and city-states.

Diplomatic allegiance: The city-state will automatically follow its Suzerain into war and peace, matching the diplomatic state of the Suzerain.

Resource sharing: All of the city-state's resources are automatically exported to the Suzerain, and the Suzerain may build tile improvements in their city-state's territory.

When at war, the Suzerain may also pay Civ6Gold Gold to take control of the city-state's military units for 30 turns. The amount of Civ6Gold Gold that needs to be paid is determined by the size and strength of the city-state's military.