A cloud-based identity and access management service for securing user authentication and resource access
Hi H Raja,
Thank you for posting your query on Microsoft Q&A!
The only way to add custom attributes to a Security Group in Entra ID is via extensions, we have a table here on the various extension types which support groups, they all must be managed via Microsoft Graph, so nothing will be visible in the portal. - https://learn.microsoft.com/en-us/graph/extensibility-overview?tabs=http#comparison-of-extension-types
If you let me know a bit more about your use case I can try suggest a suitable option.
Kind Regards, Donal