Yes!
Walk-ins can be added when there is no WiFi or internet connection. Newly added attendees can check-in and print badges. However, the event attendance number will not update until the devices are connected to a WiFi network.
You can enable offline walk-ins from your event Dashboard:
Under Registration > click on Settings

A warning message will appear when Offline Walk-in is turned ON.

*Once enabled, some features will be unavailable:
*Attendees added offline cannot be scanned into sessions or captured as a lead until network connection is restored for the data to sync.
*Note: Offline walk-ins should only be used as a last resort at a live event. Operating in Offline mode increases the risks of losing data. Ensure that all devices are connected to a stable WiFi network. If you have concerns about your event location and network stability, contact Boomset support or your Customer Success Manager.