You could use a combination of Size / Position / Rotation and cookie cutter on a duplicated object on another lower track to get the enlarged portion, then if needed go back to the Size position rotation effect to move the result to another position on the screen.
If you happen to have a bunch of New Blue effects, there is one called Magnifying Glass that could do the job.
However, I have had problems with NB effects sometimes giving me a black screen upon reopening my project. I seem to be the only one with this problem.