For large-scale to Convert OST to PST and a functional demo, I heartily suggest MacProTools OST to PST Converter for Mac. This utility is a comprehensive answer to all of your Outlook data file conversion needs, offering you a large selection of destination file formats and email clients. It offers the newest features so you can alter the final product to suit your needs. In addition, the program maintains the integrity of the data.

https://www.macprotools.com/blog/convert-ost-to-pst/