Mario Kart World supports four players racing together on one Nintendo Switch 2 system in split-screen.
This local multiplayer option lets several players share one console and screen while competing in the game's race modes. It is separate from local wireless play, which connects multiple systems and has its own player limit.
The four-player figure describes simultaneous split-screen racing, not the game's maximum online field. Mario Kart World can place up to 24 racers in a race online, making the single-console experience smaller than the full competitive lineup.
Mario Kart World was designed as a Nintendo Switch 2 launch title, so its local multiplayer features are tied to that hardware. Free Roam has different multiplayer behavior from standard racing, and should not be confused with the four-player split-screen race limit.