@Robbie Jackson Thanks for posting in our Q&A.
For this issue, I have checked it in my environment. I can see this setting "Manufacturer, model, and serial number (Windows only)" under Devices > Enrollment > Corporate device identifiers > Add > Upload CSV file in intune portal.
Please check again or use another admin account to check if this setting exists.
If there is anything update, feel free to let us know.
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.