ReactLoadingExample.jsx

import React, { useEffect, useState } from 'react';

export default () => {
  const [isLoading, setLoading] = useState(true);

  useEffect(() => {
    setTimeout(() => setLoading(false), 2000);
  }, []);

  return (
    <div>
      {isLoading ? (<p>Carregando</p>) : (<p>Conteúdo</p>)}
    </div>
  );
}