This involves turning on IMAP access in your Gmail settings and generating an app password. Once you have done that, you can set up the Zoho Mail account to import all your Gmail emails, contacts, and calendar events. This can be done by going to the "Mail" section of the Zoho Mail settings and clicking on "Import emails." From there, you can choose the Gmail account that you want to import from and follow the on-screen instructions to complete the process.
Explore Email Migration tool: https://www.shoviv.com/imap-to-imap-migration.html
Related blog: Transfer Gmail to another Gmail