Follow the mentioned steps:
Launch Microsoft Outlook and go to the File tab.
Click Info >> Tools >> Clean Up Old Items.
Select a Folder to archive, choose a date in Archive items older than box and click Browse to save archive file at desired location.
Click OK to end the process.
If you want to break large the PST items in small parts, Here I recommend you try the Split PST Tool that can easily split large PST items according to date, year, size and folder option without installing MS-Outlook in your system. It split both ANSI and UNICODE formats. It supports all windows and Outlook versions.
Visit here for more info: https://www.osttopstapp.com/split-pst.html
Ansonsmith
How to split PST file in smaller parts