Yes. As long as your device has connected to the internet at least once before the event starts, scanning and unscanning tickets will keep working even without a connection on the day.
⚠️ All other actions still require an internet connection such as log in, creating new tickets, sell onsite or processing a refund. If you lose connection, scanning keeps working, but these actions will be paused until you're back online.
To make sure your team is covered on the day, connect every device you'll use for scanning to WiFi or mobile data before doors open. This lets each device sync the orders list ahead of time.