Here is the quick guide to importing PST files into Office 365:
For Single Users (Outlook App): Open Outlook and go to File > Open & Export > Import/Export. Select Import from another program or file, choose your PST, and select your Office 365 mailbox as the destination.
For IT Admins (Microsoft Purview): Go to the Microsoft Purview compliance portal, create an import job, use the Azure AzCopy tool to upload PSTs to the cloud, and map them to mailboxes using a CSV file.
Recommended Tool: Recoveryfix Import PST to Office 365
For a faster, automated approach, Recoveryfix Import PST to Office 365 skips complex command lines and manual steps. It allows you to bulk-import multiple PST files directly into Office 365 mailboxes, archives, or shared folders, while automatically filtering out duplicates and preserving your original folder structure. https://www.recoveryfix.com/import/pst-to-office-365/