Yes you can extend the nail, by using the silk/fibreglass to form its own free edge, applying resin and pinching, before then building some strength into the nail with more resin. However, I personally wouldn't employ this method for a full set. I find it to be easier, quicker and stronger to use a good quality tip, and overlay that with the fabric and resin, or if sculpting is preferred, use gel or L&P.
I do however occasionally use this method if 'replacing' a broken natural nail, on a natural nail client as opposed to a regular enhancement client, as I find it quite close to the look and feel of a natural nail.