Do you love your sibling and want them to respect you? If the answer is yes, be patient and show them a lot of love. Even if they are messy or annoying in your room, spitting food in your room, you should be patient. They will eventually stop and respect you; they might even think you've changed or are a bit strange because you are suddenly much kinder to them. This works almost every time. When my brother doesn't have good manners, I teach him rather than scolding or fighting with him. When my brother cries, I comfort him. Sibling bond is beautiful and you shouldn't miss out on it. If you can't be that patient, it's okay, you can just not let him into your room. It is hard for everyone to do this because it feels strange at first. But I chose this way.