For most users, the firmware download and installation are automatic. If you need to trigger it manually, use these official steps from Nintendo Support : Nintendo Switch System Updates and Change History | Support
Later in May 2023, a "rebootless" version of 16.0.3 was released to update the console's internal "bad words" list without requiring a system restart. 2. Official Ways to Download 16.0.3 16.0.3 firmware download switch
Data miners identified that this update specifically addressed bugs occurring during multiple simultaneous operations on save data. For most users, the firmware download and installation