Guaranteed End Ships features
A ship for every End city
An End city is built from pieces: towers, bridges, houses and sometimes a ship. Whether the ship shows up is down to chance, and in vanilla about four cities in five end up without one. Guaranteed End Ships checks each new city's layout before it is placed. If it has no ship, the layout is rolled again with the same rules until one has a ship.

Nothing else changes
The city is still one of the layouts vanilla can make, with vanilla loot, shulkers and the Elytra in its item frame. Where cities generate stays the same, so /locate structure minecraft:end_city works as usual, and the city it finds has a ship.
Only new cities
Cities are fixed once they are generated. Cities you have already been to stay as they are, and every city in parts of the End you haven't explored yet gets a ship.