https://techcrunch.com/2023/10/26/ios-17-1-will-let-you-continue-airdrop-transfers-over-cellular-data/

Apple released iOS 17.1 on Wednesday to all users with features including improved AirDrop sharing and updates to Apple Music. The biggest change with this release is the ability to use AirDrop when you move out of the Wi-Fi range. AirDrop uses Bluetooth to securely create a peer-to-peer Wi-Fi network between two Apple devices when you are sharing content.

With this update, you can start transferring a file to a friend while you are in the same room. But if you have to leave the spot, the transfer can continue over cellular data.