You can manually move PST files to Office 365 using Outlook's Import/Export feature.
Steps:
1. Open Microsoft Outlook.
2. Click on File >> Add account.
3. Provide an email ID of Office 365 and sign in.
4. Go to File >> Open & Export >> Import/Export.
5. Select option Import from another program or file.
6. Select Outlook Data File(.pst).
7. Provide PST file location.
8. Select filter: remove duplicate items.
9. Finally, select Office 365 mailbox folders.
While this method works for small migrations, it can be time-consuming and requires Outlook installation. There is also a risk of interruptions when handling large PST files or multiple mailboxes. For a more reliable and efficient approach, many users prefer the MailsDaddy
PST to Office 365 Migration Tool.