I am using cutom expiration metadata property instead of prism:expirationDate. So we want to also have the expiration flags on Assets shown as below image. Please let me know how we can acheive the same.
Instead of customizing the status, why don't you set or update prism:expirationDate value with your custom expiration date. That will automatically set the EXPIRED flag on Asset.
custom:expirationDate = prism:expirationDate