Large PST files slow down Outlook’s performance and it is hard to stay productive with slow loads of data and avoid constant PST corruption.Usually there is no manual way in MS Outlook to split PST file; however, you can do this from different indirect features of it, such as 'Import and Export' and 'Archive'.
User can use Archive feature in Outlook to Split large pst file into multiple small files by yearly Archive. User can run the Archive process multiple times, each time to a new pst-file. This splitting process can be done via Archive feature in Outlook.
Manual way steps :-
Step 1: Open MS Outlook, Select the PST file to move the mail items.
Step 2: Go to the file tab, then ‘Clean Up’ tools after that select ‘Archive’ option.
Step 3: Check Archive folders and all subfolders if not checked from the archive dialogue box
Step 4: Select the folders to move and then browse the location to save PST file.
Step 5: Now name the new PST file and click OK