To export an MBOX file to Outlook, you need to convert the MBOX file into PST format because Microsoft Outlook does not support MBOX files directly. One common method is to use Mozilla Thunderbird as an intermediate client and then move emails through IMAP, but this process can be complicated.
A simpler approach is to use a professional converter like MailsDaddy MBOX Converter. Just add the MBOX file to the software, preview the emails, select PST as the export format, and start the conversion. After that, import the PST file into Outlook using the Import/Export option.
Get more info:
https://www.mailsdaddy.com/blogs/import-mbox-outlook-full-accuracy/