Yes, almost all cameras will let you choose a smaller size. You should look at your camera's manual or at least post your camera's make and model here.

   I like to always capture images at the highest setting and then edit them in a photo retouching program to make them smaller. It would be a shame to take a great photo on a low quality setting. However, you can always create a small (low quality) image starting from a larger one.

      Paul