The official Nintendo of Australia website for Animal Crossing: New Horizons confirmEd that every player profile on each Nintendo Switch console will share the exact same island. [Thanks, Games Radar!]
In effect, that means that you’ll need to delete the game data and start over anew or buy another Switch and another copy of the game if you want to play with a different island layout and different villagers.
This is a similar case to the first game in the series on GameCube, where four players could only play locally in a single town. With Animal Crossing: New Horizons, up to eight residents can live on the same island via different Nintendo Switch profiles. It’s a bit of a bummer for those who want to have their own separate play files, but was likely done to facilitate the game’s new offline drop-in drop-out multiplayer mode, where up to four residents can play together at once on the same screen.
Other forms of multiplayer include the ability to play together with others on your island via local wireless or online play, similar to other games in the series. However, you’ll need a Nintendo Account and a Nintendo Switch Online subscription to connect with others online.
Animal Crossing: New Horizons will appear on March 20, 2020. A special Nintendo Switch was revealed for release alongside the game, but you’ll be able to buy the Dock and special Joy-Cons separately in Japan.