That's on the Switch's (or Switch Lite's) home screen - you can get ... likely want to revert back afterwards. And that's it: Nintendo's controller remapping options are pretty extensive from ...

1.Which games don't work with Nintendo Switch Lite? 1.1.List of Switch games that don't support Handheld Mode 1.2.Games that are 'better' with detached controllers ... just need a pair of Joy ...