ToggleMessage.js

import React from 'react';
import { createRoot } from 'react-dom/client';

const Message = () => {  
  const [open, setOpen] = React.useState(false);

  function toggle() {
    setOpen(prev => !prev)
  }
  
  return (
    <React.Fragment>
      <a href="#" onClick={toggle}>Want to buy a new car?</a>
      {open && <p>Call +11 22 33 44 now!</p>}
    </React.Fragment>
  );
}

document.body.innerHTML = "<div id='root'></div>";
const root = createRoot(document.getElementById("root"));

root.render(<Message />);
const rootElement = document.getElementById("root");
setTimeout(() => {
  console.log("Before click: " + rootElement.innerHTML);

  document.querySelector("a").click();
  setTimeout(() => {
    console.log("After click: " + rootElement.innerHTML);
  });
});