Booting into Tails Offline
Plug in your Tails OS USB.
Boot into the Tails USB.
Select “Yes” for more options.
Select “Forward”.
Select “Disable All Networking …” (no need to fill in any password).
Start Tails.
Note: Tails OS can be booted into for online use as well. Many users use Tails for privacy oriented browsing and file handling.