How do I show the index page when there are no route params?

const Posts = () => {
  ...
  return <>
    {posts.map(post => <Post post={posts} />)}
    {/* Where do I put the outlet? I only want the Posts or the Single post to show */}
  </>
} 

export const postsRoute = new Route({
  getParentRoute: () => rootRoute,
  path: '/posts',
  component: Posts,
})

export const postRoute = new Route({
  getParentRoute: () => postsRoute,
  path: '$postId',
  component: Post,
})

const routeTree = rootRoute.addChildren([
  indexRoute,
  postsRoute.addChildren([postRoute]),
])