Hi Steven,
Yes, in Exchange Online Protection standalone plan, you can also use the Directory Synchronization feature.
When you subscribe or purchase an EOP tenant, in the EOP portal/Office 365 admin center -> users and groups, click Set up hyperlink behind the "Active Directory® synchronization:" tab. The DirSync method and deployment in EOP are similar to the current one you are using now.
Besides Office 365 community, to get more information and technical response about the Microsoft Exchange Online Protection (EOP), you can also refer to this article and find the Support for EOP: Help and Support for EOP
Best Regards,
Bourne Zhang