@ChikaraTaro, Thanks for posting in Q&A. For Autopilot enrollment, there are two types when we join to Azure AD (Microsoft Entra), one is Microsoft Entra join and the other is Microsoft Entra Hybrid Join.
For Microsoft Entra join, it can let all Microsoft Entra users to login any Microsoft Entra joined device by default.
https://learn.microsoft.com/en-us/entra/identity/devices/concept-directory-join
But if you want to specific users to login the device, you can configure Intune policy setting "Allow Local Log On" to add the user you want to login this PC. Here is a link with more details.
Note: Non-Microsoft link, just for the reference.
As a note, if you have the same setting configured in both local group policy and Intune policy, the local group policy will win over Intune policy and take effect. Therefore, please only configure policy in one place to avoid any issue. In addition, domain group policy can not apply to Microsoft Entra joined devices.
For Microsoft Entra Hybrid joined device, we use domain user account to login. And domain group policy can apply to these devices.
https://learn.microsoft.com/en-us/entra/identity/devices/concept-hybrid-join
Hope the above information can help.
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.