If you have just a few .eml files, open each email in an email client and manually save the attachments. That’s fine for small batches but it’s quickly frustrating when you have hundreds of emails to deal with because it takes a lot of time and it’s easy to miss files. I had this exact issue when exporting old emails from Thunderbird. Instead of opening every message one by one, I tried Mailvare Free EML Attachment Extractor. It let me pull attachments from multiple .eml files at once and even filter the file types I actually needed, which saved a lot of unnecessary work. One thing I'd suggest is keeping a copy of the original .eml files before extracting anything just in case you need to refer back to the original emails later.