There is no need to depend on Outlook to open EML files. EML is a standard email file format that can easily be read and accessed by multiple email clients like Thunderbird, Zoho Mail, Apple Mail, etc., simply via drag & drop.
There are also multiple free online tools available, but they are often restricted by file size, may only open one EML at a time, and require uploading your email data to external servers. Instead, it is better to use a desktop-based email converter/viewer that keeps the data locally. For example, BitRecover also offers a free EML Viewer software that lets you read EML files in bulk while keeping the email data preserved. You can view metadata, To/From details, inline images, attachments, signatures, HTML content, and other email properties without depending on Outlook.