Girls, hello. What advice would you give for introducing a older chil…

Girls, hello. What advice would you give for introducing a older child to a new baby? We have a daughter who is 6 years old and we're expecting a son soon. She says she already loves him, but I don't know how it will be in reality and I'm very worried. We have a cat, at first even reclusive towards it) I'm used to having one child and for parents and grandparents as well. The girl has a strong character. But again, she loves all babies on the street). In general, I'd be happy for any advice on how we can prepare ourselves and our child. Thank you in advance.