Depends on the bow and how the cam system works. Some bows if you change the draw length it changes the nock height.
However, changing your draw length is a pretty serious adjustment and may require you to retune your whole bow, including center shot. Maybe not for rough tuning, but fine tuning or broad head tuning it may make a difference. Depending on how much you change it you may have to get new arrows as well because of the change in spine. Shortening will not have as much of an affect as making it longer though, since a stiffer spined arrow is not as touchy as a weaker spined arrow. If your arrows were overly stiff to begin with you may not even notice a difference.
Changing your draw weight has the same effect, as a matter of fact that is one of the way you tune a bow is by changing the draw weight. That is actually one of the reasons they are adjustable, so you can tune your bow to the arrows

.
You may not have to change your sights though, if you do it won't be by much.
Paul