Not Found Page in React Router

When no other route matches the URL, you can render a “not found” route using path="*". This route will match any URL, but will have the weakest precedence so the router will only pick it if no other routes match.

function App() {
  return (
    <Routes>
      <Route path="/" element={<Home />} />
      <Route path="dashboard" element={<Dashboard />} />
      <Route path="*" element={<NotFound />} />
    </Routes>
  );
}

References
https://reactrouter.com/docs/en/v6/getting-started/overview#not-found-routes