@Ladylulabelle when you get a dog, will you be getting a rescue or one from a litter?
it's very difficult to get a dog from a rescue if you have a cat.
it depends on both the cat & the dog. My friends 20 year old cat puts all the dogs in their place. They start off curious, then terrified of her then they settle into tolerance & sometimes love.
other times cats just find their own 'safe space' in the house, but that's not much of a life for them.
im not sure what rag dolls are usually like with dogs? Besides, there's no guarantee it would be 'breed typical' anyway.
if I REALLY wanted both & could get a cat, but not a dog until sometime in the future, I'd get the cat now & deal with any issues when I was ready to get the dog.
BUT I wouldn't be getting a cat simply because a 6 year old says they want one. Cats are not what little kids think they'll be like (unless it's an existing cat, used to children) and it can be a very difficult situation to manage.