@Vorbrodt IT GmbH, Thanks for posting in Q&A.
Based as I know, there are some functions for Windows Autopilot sign -in experience returned. Like Pre-populate the Azure Active Directory (Azure AD) User Principal Name (UPN) under the pre-provisioning landing page and Azure AD sign in page. More details in the following link:
But for your request to automatically sign in user account, based on my research, I didn't find this feature. You can feedback to Intune uservoice to see if we can get this in the future:
https://feedbackportal.microsoft.com/feedback/forum/ef1d6d38-fd1b-ec11-b6e7-0022481f8472
Thanks for the understanding.
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.