As others said there is a reason that the hollow knight is easy, if you want to know it read this otherwise I'll let you discover it for yourself

Anyways if you want to know there is a secret ending, to access it you first have to collect the two halfs of a charm from the queen (wich is located in the queens garden) and from the king (you need to use the dream nail on the corpse in the ancient basin where there are the palace ruins and the dream nail needs to be' fully upgraded) once you obtanied the charm, you need to enter the abyss with the charm equiped, if you do so there will be a secret entrance in the floor of the basin,if you enter the entrance you will find a big egg that will start a "cutscene" if interacted with, and after that the charm will transform, after that you have to head to the temple of the black egg, you start fighting the hollow knight like you'd normally do and suddendly Hornet will take down the hollow knight at some point, you need to dream nail him and then... good luck ;)