The 
Envoy Envoy is a representative of your civilization that can be sent to city-states that you've met. By default, one Envoy Envoy is earned for every 100 influence points that you accumulate. After earning an Envoy Envoy, you will receive a prompt to choose which city-state to send it to. If you have multiple Envoy Envoys, you may divide them between city-states as you wish.
The bonuses you earn from a city-state depend on how many Envoy Envoys you have sent to the city-state. One bonus is earned for having 1 Envoy Envoy, the next bonus is at 3 Envoy Envoys, and the final bonus is at 6 Envoy Envoys. The civilization with the most Envoy Envoys on a city-state, and at least 3 Envoy Envoys, is considered that city-state's Suzerain, which gives additional bonuses.
Declaring war directly on a city-state removes all Envoy Envoys you had there. Otherwise, Envoy Envoys stay on the city-state permanently. Envoy Envoys at a city-state are visible to all players, and placing them may have diplomatic consequences. The bonuses earned are based on how many Envoy Envoys you have present, regardless of who else has Envoy Envoys there. City-states of a type all share the same type of bonuses. They are cumulative, so that as a player places more and more Envoy Envoys on a city-state, they stack with the bonuses from before.
In Civilization VI: Rise and Fall, Spies can remove other civilizations' Envoy Envoys from a city-state if they succeed at a Fabricate Scandal mission.
Earning Envoys
- Influence generates
Envoy Envoys over time. Check here for more information. - Additionally, the government Monarchy grants an additional 20% to your influence generation, +1% every ten turns on Standard speed. The diplomatic policy card Charismatic Leader grants 2 influence per turn. This gets replaced by Gunboat Diplomacy that ups it to 4 per turn.
- Being the first to meet a city-state grants one Envoy Envoy.
- Completing city-state quests grants one Envoy Envoy.
- The diplomatic policy card Diplomatic League doubles your first Envoy Envoy to a city state. To min-max this, you can store up Envoy Envoys until you have met a certain number of city-states, then activate the card and get the bonus for each one, and then deactivate the card since it no longer gives benefit.
- The diplomatic policy card Containment doubles Envoy Envoys to City-States whose Suzerain has a different government. This could be min-maxed in a similar way to Diplomatic League; just remember that you lose the bonus once you become Suzerain.
- Some Great General retirement and Great Merchants powers provide Envoy Envoys.
- Building the Apadana will grant 2 Envoy Envoys once it is finished. 2 Envoy Envoys will also be granted anytime a Wonder is built in the same city.