When you're using your Nintendo Switch in handheld mode and the game prompts you to switch to 2-player mode, it likely means that the game supports multiplayer functionality and is encouraging you to use a second controller. Here are your options:
1. **Stay in Handheld Mode (Single Player)**: If you want to continue playing the game by yourself, you can simply ignore the prompt and continue playing in handheld mode as a single player. Some games