Google introduces option to change primary Gmail ID without data loss:

Google has begun rolling out a feature that allows users to change their primary ‘@gmail.com’ email address while keeping all existing account data intact. Eligible users can choose a new Gmail address from account settings, with the old address automatically becoming an alias. Emails sent to the original ID will continue to reach the same inbox, and users can log in using either address across Gmail, YouTube, Drive, Maps, and other Google services.