Autopilot and auto provisioning of OneDrive and Outlook. Users can login and be ready to go. We have even drop shipped laptops this way.
Edit: Since there has been a lot of interest here are the configuration profile settings I have used to get OneDrive, Outlook and as a bonus Edge to auto sync. Most of our users have a Microsoft 365 Business Premium license.
OneDrive
Silently sign in users to the OneDrive sync app with their Windows credentials
Silently move Windows known folders to OneDrive
Prevent users from redirecting their Windows known folders to their PC
Use OneDrive Files On-Demand
Outlook
Automatically configure profile based on Active Directory Primary SMTP address
Disable Outlook Mobile Hyperlink
Edge
Configure whether a user always has a default profile automatically signed in with their work or school account
