Yup, though it's hard to do it intentionally. Time dilation is moderately common, though. I've never really been able to extend a dream a significant amount of time on purpose, but I have had a few LD's which lasted more than a few months of dream-time. This doesn't necessarily mean that the dream will be super vivid, or that your recall will be great. Since the mind extends dreams by skipping over details so the mind can process things faster, or even leaving out chunks of time and replacing it with vague memories instead of living our that time directly. For example, if you have a dream that lasts for the period of an entire month, you might not remember anything more than that you went camping on the second month in the dream. You won't be able to directly recall any specifics of the camping trip, only that you were there. When the mind does this, it can make the dream seem much longer.

And if you meant just extending the dream a bit longer when it begins to fade, this too is possible, but much easier. Spinning around is a top method, or try climbing through a mirror. Both help to maintain lucidity in a dream that's beginning to fade.