The following tutorial shows the partitioning in answer file, follow it to configure your autounattend.xml.
https://www.tenforums.com/tutorials/96683-create-media-automated-unattended-install-windows-10-a.html
-------------------------------------------------------------------------------------
If the Answer is helpful, please click "Accept Answer" and upvote it. Information posted in the given link is hosted by a third party. Microsoft does not guarantee the accuracy and effectiveness of information.
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.