Hi oussama fouad,
Currently, there are no such tools to migrate an account from one Office 365 tenant to another or Microsoft articles that describe how to realize this.
But technically speaking, the IMAP migration and exporting and then importing .pst files are suggested to move the emails.
The following links are for your reference:
Migrate Email from an IMAP Server to Exchange Online Mailboxes
Set up email in Outlook 2010 or Outlook 2013
Export .pst files from Outlook 2013
Export .pst files from Outlook 2010
Import Outlook items from an Outlook Data File (.pst) in Outlook 2010
Import Outlook items from an Outlook Data File (.pst) in Outlook 2013
Thanks,
David Zhang