You can manually convert OST to PST only when you are using Outlook with the original Exchange account but If you want to convert original exchange profile then you should use any third party software. I personally recommend you this professional and brilliant OST to PST conversion software.
With this tool you can convert whole data of OST mailbox such as Emails, Draft, Task, Contact, Calendar, Attachment, and many more MS Outlook installation will be not mandatory. You can convert your data into various formats like PST, EML, HTML, EMLX, vCard, vCal, MSG, MBOX, etc.
This is the only software which can help you to convert files of any size without facing any difficulties you are free to convert the files of any size this facility is provide only by the OST to PST Converter. It can support all version of MS Exchange and MS Outlook.
Download link:- OST to PST Converter
The OST to PST Converter tool is the best tool for converting the data from OST file to Outlook PST file without any trouble. You can use this trial version OST to PST converter software, this software will help you to convert emails from OST to PST file format. This is a trial version tool to convert your all emails from OST to PST. This software supports all Windows OS and MS Outlook 2003, 2007, 2010, 2013 and 2016,2019 versions.you can download the free trial version which converts few items from each folder.you can download this tool from here:-https://www.sametools.com/convert/ost/
There are multiple solutions available for converting OST to PST file format. You can google this solution. Last time I used a solution for the same issue and got a great result with this OST to PST Converter tool. I will recommend you to download this software you can download it from here:-https://www.toolsbaer.com/ost-to-pst-conversion/