Migration of users from Online Exchange to Local Exchange (Hybrid Model)

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You can use the remote move migration wizard in the EAC in Exchange Online to move existing cloud mailboxes to the on-premises Exchange organization:

1. In the EAC, go to Office 365 > Recipients > Migration.
2. Click Add Add Icon., and then select Migrate from Exchange Online.
3. On the Select the users page, select Select the users that you want to move and then click Next.
4. On the Select the users page, click Add Add Icon. and then select the Exchange Online users to move to the on-premises organization, click Add and then click OK. Click Next.
5. On the Confirm the migration endpoint page, verify that the FQDN of your on-premises Exchange server is listed when the wizard confirms the migration endpoint. For example, "mail.contoso.com". Click Next.
6. On the Move configuration page, enter a name for the migration batch in the New migration batch name text field. Then enter the target delivery domain in the Target delivery domain for the mailboxes that are migrating to Office 365 field. In most hybrid deployments, this is the primary SMTP domain used for both on-premises and Exchange Online organization mailboxes. For example, contoso.com.
7. Choose whether to also move the archive mailbox for the selected user and enter the database name you'd like to move this mailbox to in the Target database text field. For example, Mailbox Database 123456789. Click Next.
8. On the Start the batch page, select at least one recipient to receive the batch complete report. Verify that Automatically start the batch is selected, and then select the Automatically complete the migration batch check box. Click New.

Reference the article : https://learn.microsoft.com/en-us/exchange/hybrid-deployment/move-mailboxes#move-exchange-online-mailboxes-to-the-on-premises-organization