Converting OST files, used for offline access in Outlook with Exchange servers, to PST files for broader use requires a bit more effort. There are two main approaches:
Outlook’s Export Tool: Within Outlook, you can utilize the Import/Export wizard to selectively export mailbox items to a new PST file.
Third-Party Software: For corrupted OST files or more advanced needs, dedicated OST to PST converter software is recommended. These tools offer features like faster conversion, data recovery from damaged files, and batch processing of multiple OST files.
https://corbettsoftware.com/convert/ost/pst.html