You can re-size it to 12 x 12 if you wish by opening up the template, and then going to Page > Settings. On the Size tab, you can adjust the size from 8 x 8 to 12 x 12. (you'll have to do this for each page of the template).
I've done this many times and been pleased with the results. Of course, whenever you are sizing an image "up", there may be a loss of quality. If you're printing or publishing as an image, etc. you may want to do a "test page" before publishing your whole scrapbook just to make sure that you're satisfied with how everything looks.