If you are a admin and you need the BitLocker recovery key for one of your Microsoft 365 users go into Microsoft Entra.

In Microsoft Entra choose Users, All Users click the name of the user you are looking for the BitLocker key for, choose Devices for that user. Click the device you need the BitLocker key for, on the left of that device choose BitLocker keys, click Show Recovery Key and you can then see the BitLocker Recovery Key, Device Name and BitLocker Key Id for the drive.