There are many ways available on the internet to perform this conversion. However, the method can be time-consuming and may risk your data. Hence, I would recommend using a professional MacSonik OLM to PDF Converter. This is a risk-free utility that helps to backup multiple OLM files into PDFs in just a few clicks. It maintains data integrity and folder hierarchy throughout the process. The OLM to PDF converter tool prevents any data alteration and also helps remove duplicate emails from the process.

Actually there are a lot of handy, free software and online tools for working with PDF documents that really simplify the workflow. I advise you to check this article https://www.pdfplatform.com/blog/how-to-reduce-pdf-file-size-on-mac/ if you need to reduce the size of a PDF document on a Mac. Takes practically no time.