Yes, zucchini will get softer the longer you cook it. Roasting and sautéing are two common cooking methods for zucchini that will soften the vegetable as it cooks.  The key is to not overcook the zucchini so that it retains its shape and texture but is also cooked through enough to become tender and delicious.  Boiling or steaming may also be used to cook zucchini, both of which can make it soft in a shorter amount of time than other methods.