How to set up new device and transfer back up data in i cloud to the new device

See: Transfer data from your previous iOS or iPadOS device to your new iPhone, iPad, or iPod touch - Apple Support

I'm setting up a new iPhone12 for someone whose phone was stolen, when I try to connect to iCloud Apple Verification sends a code to his other devices which are not with him. How do we skip/bypass this phase?

Yes my what’s up data lossed please data backup all chatting backup