Are you trying to Convert OST to VCF so you can move your Outlook contacts to another device or application? I recently found CloudXena OST to PST Converter for Mac, and it seems useful for exporting contacts from OST files into VCF format.
The software allows you to add one or multiple OST files at the same time, which is helpful if you have contacts stored in different mailbox files. Before conversion, you can preview all contacts and select only the ones you want to export into VCF.
One useful feature is the date range filter, which helps if you only want to export recently added contacts. The tool also removes duplicate contacts automatically, so you do not end up with repeated entries in the final VCF file.
Another advantage is that you can save the exported VCF files in a custom folder on your system for easier access.
Read More: https://www.cloudxena.com/blog/convert-ost-to-vcf/