Hi @Ramachandran Krishnamoorthy
Currently we could not migrate customed workflow to power automate, you could read this article to get some information about it:
https://learn.microsoft.com/en-us/sharepointmigration/spmt-workflow-overview
However, Mocrosoft is working on this development process, hope this feature could be realized sooner. You could also send feedback to Microsoft SharePoint Feedback.
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