which service is the big boss of Azure ?

Purview is a great service for data governance and management in Azure, but it may not necessarily be considered the "big boss" or central service that manages all other services in Azure. Azure Resource Manager (ARM) is one service that could be considered the "big boss" or central service that manages all other services in Azure. ARM provides a unified API layer for deploying, managing, and monitoring Azure resources, including virtual machines, storage accounts, and more. It allows you to organize your resources into resource groups, apply access controls and policies, and deploy resources as a single unit.

Other services that could be considered essential or foundational to many other services in Azure include Azure Active Directory (AD) for identity and access management, Azure Monitor for monitoring and logging, and Azure Security Center for security and compliance management. The importance and centrality of any particular service may depend on the specific needs and architecture of your Azure environment.