I want to Server-Sent Events follow flow of my posts /MERN

I want to use Server-Sent Events for my MERN project. I am having an issue and couldnt fix it yet.

export const getPosts = async (req, res) => {
  try {
    res.setHeader('Cache-Control', 'no-cache');
    res.setHeader('Content-Type', 'text/event-stream');
    res.setHeader('Access-Control-Allow-Origin', '*');
    res.setHeader('Connection', 'keep-alive');
    res.flushHeaders();
    const posts = await Post.find();
    res.write(`data: ${JSON.stringify(posts.reverse())}\n\n`);
    res.on('close', () => {
      console.log('client dropped me');
      res.end();
    });
    
  } catch (e) {
    res.status(404).json({ msg: e.message });
  }
};

this is how I get posts, but I do want to SSE follow flow of posts. I want SSE follow the data in MongoDB, trigger when there is a change.