@Rakesh_Kapoor, did you ever get an answer to this? I have the same question.

I’d like to know this too.

Welcome to the Airtable community!

Currently you cannot create a new base using any of the APIs.

You can write a custom app using to create new tables and fields in an existing base. You can only create a limited set of field types, and no calculated fields. The details are in the developer documentation.

I think it's now available. Would this be what you're looking for?
https://airtable.com/developers/web/api/create-base