Launch Baldur’s Gate 3
Go to Settings
Open Video settings
Set Display Mode to Windowed or Borderless Windowed
Drag the game window to the other monitor
If needed, use Alt + Enter to switch between fullscreen and windowed mode
If the game is in exclusive fullscreen, change it to Borderless Windowed first
Set the correct monitor in your operating system display settings if the game opens on the wrong screen
In Windows, press Win + Shift + Left Arrow or Win + Shift + Right Arrow to move the window between monitors
Save the settings and restart the game if the change does not apply immediately