Hello there,
BitLocker automatic device encryption starts during Out-of-box (OOBE) experience. However, protection is enabled (armed) only after users sign in with a Microsoft Account or an Azure Active Directory account.
BitLocker automatic device encryption uses BitLocker drive encryption technology to automatically encrypt internal drives after the user completes the Out Of Box Experience (OOBE) on Modern Standby or HSTI-compliant hardware.
More information here https://learn.microsoft.com/en-us/windows-hardware/design/device-experiences/oem-bitlocker
Hope this resolves your Query !!
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