Hi
If you want to deploy and update SCEP using SCCM, we could refer to this link , which may be helpful to solve your problem.
COMPLETE SCCM INSTALLATION GUIDE AND CONFIGURATION
https://systemcenterdudes.com/complete-sccm-installation-guide-and-configuration/#sup
Also , we could manage System Center Endpoint Protection (SCEP, EPP (aka Antivirus)) policies via Group Policy.
Here is the link about specific process.
https://yongrhee.wordpress.com/2020/03/19/managing-system-center-endpoint-protection-scep-epp-aka-antivirus-policies-via-group-policy/
Best Regards
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