Only the dock with a LAN port – model no. HEG-007 – can be updated. This is the dock included with Nintendo Switch - OLED model.
Because Nintendo Switch Lite is not compatible with any dock, this feature is not available on Nintendo Switch Lite systems.
Complete these steps
Ensure your console has the latest system update installed.
From the Nintendo Switch HOME Menu, select System Settings.
Scroll down to System.
Select Update Dock, then Begin Update to begin updating the dock’s firmware.
If the update stops before it can be completed, try this step again.