HI Shivam2, 

Unity Catalog features are provided to you at no charge once you upgrade to Premium or Enterprise tier. 

If your Databricks account is created after November 8, 2023, then Unity Catalog is enabled by default. You can use following instruction to check if Unity Catalog is enabled for a given workspace:
https://docs.databricks.com/en/data-governance/unity-catalog/get-started.html#workspace. 

If it is not enabled, please follow the below instructions to enable:
https://docs.databricks.com/en/data-governance/unity-catalog/enable-workspaces.html