Besides a litter box, every cat needs a scratching post unless you want to turn your furniture into a scratching post. Of course, scratching posts come in all varieties so that way you can find the best one for your cat.
Just remember that some cats like posts with platforms so they can lay on top of them while others like different types of scratching surfaces. The ultimate goal is to get your cat to scratch a post instead of your furniture, but that might be hoping for too much so get furniture that won’t tempt your cat and you should be happy.