The best way for converting OST data into PST format, User use the third party tool. It helps to easily convert OST data but if the tool is perfect and reliable for conversion and provides the batter services. I would suggest the best and reliable tool, Shoviv OST to PST converter.
The OST to PST converter tool converts the multiple OST files to Outlook PST formats and it also recovers the deleted and inaccessible OST data items such as email, contact, task, calendar, Journal, etc. It also exports OST data into Office 365, Live Exchange Server, EML, MSG, and HTML Formats. Users first download its demo version and test the tool and also convert the first 50 data items per folder.
More details, visit:- https://www.theglobalfinders.com/2020/08/convert-ost-to-pst.html