There are two ways by which you convert Olm files to another file format.
1). Manual method- You can convert OLm files to other file formats manually but this method will take a lot of time to convert and may corrupt your data as it is not a risk-free tool, for this method you need technical knowledge.
2). Third-party tool- Aryson OLM Converter is the best tool to convert your OLM files into other file formats like Gmail. MBOX, PST, EML, MSG, MHT, PDF, etc. It is a total risk-free tool and will not take time to convert the files.
https://www.arysontechnologies.com/olm-converter/