Can you merge Azure tenants?
To consolidate the tenants, you will need to manually add the new user objects in the Azure AD and provide the necessary permissions. There is no out-of-the box tool in Azure or Microsoft 365 that does this, so you will need to re-create the users and resources.
Can you merge two o365 tenants?
Use Third-Party Tool to Merge Two Office 365 Accounts
It is one of the best application that helps to combine two Office 365 tenants without any hassle. With the help of this tool, users can merge Office 365 tenants, Accounts & domain users data.