What's In a Sewing Pattern
Commercially available sewing patterns are typically an envelope containing a bunch of large folded pages. One or more of the pages will contain directions for how to assemble the pattern. The other pages, usually printed on large sheets of tissue paper, have full-scale outlines of the pattern pieces. To assemble the pattern, you need to cut out the fabric along the lines of the pattern pieces and then put the pieces together according to the directions.
Do They Make Worthwhile Fursuit Patters?
Well, they do make some patterns for fursuits. However, most costumers wouldn't want to use the patterns as they are provided. They're often loose-fitting and not too detailed. Instead, the patterns are much more useful as a starting point for developing a uniquely individual costume. Assemble the pattern as provided and then begin modifying the shape and fit to match your character design.
Specific portions of a commercial pattern may also be useful inspiration. If you see a pattern that has a nose, for example, that looks like what you envision for you character, grab the pattern; figure out how they've constructed the nose and then apply the same technique to your own fursuit.
Shop around and see what you can find...