You can easily split the large PST files into small pieces in a matter of minutes. There are many tools for splitting large PST files, but I would recommend using the Split PST for Mac to split large PST files into small parts based on the date, size, year, and folder. This tool is fully capable of splitting all MS outlook items such as emails, folders, contacts, calendars, journals, etc. This software supports all Mac OS versions.
For more info visit here:-
https://www.mailvita.com/split-pst-for-mac/