Hi @Rasika Eshwar - Thanks for the question and using MS Q&A platform.
Currently are no APIs available to create Governance domains in Microsoft Purview classic portal. Microsoft Purview is still evolving, and new features are being added regularly. You can check the Microsoft Purview documentation for the latest updates on available APIs.
These are the available REST APIs for MS Purview: Microsoft Purview Resource Provider Rest API
Here is the update from internal team: Programatic way to use data goverance or data quality will be coming shortly. We don't have ETA and I will be updated this thread once it's available.
Hope this helps. Do let us know if you any further queries.
If this answers your query, do click Accept Answer
and Yes
for was this answer helpful. And, if you have any further query do let us know.