Excerpt from SBW manual (link straight into SBW app, in settings section) https://sbw.app/posts/manual/

Channel migration

Wallet can be moved from one phone to another without closing payment channels and this can be achieved in the following way:
Make sure you have wallet recovery phrase saved, if not then obtain it in wallet settings. Make sure channel backup file is present at Download folder, if not then enable local backup in wallet settings and check again. Close SBW and copy encrypted.channels-mainnet-<hash>.bin backup file to some place outside of phone; putting it to public places is safe becase backup file is encrypted with your recovery phrase. Copy backup file to a new phone. Install SBW on a new phone, then open it and choose Restore existing wallet and then Backup + recovery phrase. Once file picker appears: point it to backup file on a new phone and then provide a recovery phrase, that’s it. Important: unlike Bitcoin wallet, same Lightning channels can not be used on many devices at the same time. Doing so will eventually lead to forced channel closure so make sure to delete an app from an old phone once channels are restored on a new one.

Wallet restoring

If you only use Bitcoin wallet then recovery phrase alone is enough for full balance restoring.
If you also have Lightning channels and there is no backup file then you’d need to reconnect to remote peer you have those channels with (by scanning a peer node QR for example). Once connected there will be a popup asking you to force-close locally missing channels. Once accepted you’ll shortly get the rest of missing channels balance back to local Bitcoin wallet.