@SurajSu Sure, for custom HTML tags migration to Event Forwarding you can use Cloud Connector event forwarding extension. Thus allows you to create custom HTTP requests to send data to a destination or retrieve data from a destination.
Few things to keep in mind:
1. If the vendor requires data (like a vendor-specific unique ID, for example) that can only be generated or accessed by their own client-side tag, then that vendor tag is likely not a good candidate to move. Attempting to reverse-engineer a client-side tag with the idea of moving that data collection to event forwarding without the appropriate APIs is discouraged.
2. Event forwarding is a paid feature that is included as part of the Adobe Real-Time Customer Data Platform Connections, Prime, or Ultimate offerings.
Thanks,
Asheesh