They give you a complete list, but all the grains are in one bag. It might make sense to brew the kit as-is, then tweak the next batch. That way, you'd know exactly what the tweak did for the beer. On one occasion, I purchased two kits for a Red ale & dry hopped one batch with extra hops.
Remember one unassailable statistic, as explained by the late, great George Carlin: "Just think of how stupid the average person is, and then realize half of them are even stupider!"
"I would like to die on Mars, just not on impact." Elon Musk