Manually Set an Item as Active Any item can be set to active to indicate that the page is anchored to the respective section. Demo
Twig
{% include '@bolt-components-toc/toc.twig' with {
  items: [
    {
      text: 'Section One',
      url: '#section-one',
    },
    {
      text: 'Section Two',
      url: '#section-two',
      active: true,
    },
    {
      text: 'Section Three',
      url: '#section-three',
    },
  ]
} only %}
HTML
<div class="c-bolt-toc-wrapper">
  <bolt-toc>
    <bolt-toc-item url="#section-one">
      Section One
    </bolt-toc-item>
    <bolt-toc-item url="#section-two" active>
      Section Two
    </bolt-toc-item>
    <bolt-toc-item url="#section-three">
      Section Three
    </bolt-toc-item>
  </bolt-toc>
</div>