Easy Method (Recommended) Use an MBOX to PST converter tool. These tools directly convert all emails, attachments, and folders from MBOX into PST without data loss. Most converters support batch migration, selective folder conversion, and maintain structure. After conversion, simply open or import the PST file into Outlook using File → Open & Export → Open Outlook Data File. This method is fast, secure, and suitable for large or multiple MBOX files.

https://www.vsoftware.org/store/mbox-to-outlook-importer/