In an interview for Japanese gaming outlet Game Watch, Hidetaka Miyazaki also said that Sekiro: Shadows Die Twice will have several endings. This means that during the walkthrough players will stumble upon certain story points, which will force them to make decisions, which will eventually lead to one of the endings.
So if you want to see all the endings, you will have to finish the game several times. It's not a bad thing at all. There is a chance that by making different decisions players will reveal new content, which is always a good thing.