One way to split a PST file is by size. You can use the option “Archiving” or Import/Export wizard in Outlook to archive or export old emails into a new local PST file. These options help you split PST based on date range or mail folders (size). (But it is time taking, and you cannot open the large PST file directly to Outlook because of 50 GB size limitations).
If you want a more reliable solution like you want to split large upto PST files upto 50 GB, as per the specific criteria like date, size, year, email ids and folders, you can use a 3rd party PST splitter tool, Once you have downloaded the tool, you need to select the PST file that you want to split and then select the criteria based on which you want to split the PST file. Click here for more details: https://www.stellarinfo.com/split-pst-file.php