Yeah, generally exercises like decline presses, dips, and decline flyes or cable flyes tend to recruit more muscle fibers from the lower areas of the chest.
So if you have good overall chest development, but have weak points, such as the lower pectorals for instance, it's good to attack those weak points with more specific exercises. People who are still looking for overall chest development, like me, should concentrate more on building overall chest mass, rather than attacking weak points earlier than needed. And remember that no one chest exercise works in complete isolation, as in, if you're doing decline presses to really hit your lower pectorals, you're still going to be working other parts of the chest as well, it's just that some exercises tend to stimulate certain parts of the muscles more so than others due to how the muscle contracts under certain circumstances.
Hope that helps you in some way! Good luck bro!