<amp-accordion>
  <section>
    <h2>Section 1</h2>
    <p>Content in section 1.</p>
  </section>
  <section expanded>
    <h2>Section 2</h2>
    <div>
      <p>Content in section 2. I have Exapanded Attribute.</p>
    </div>
  </section>
</amp-accordion>