How to modify part of the design of the details of the article magento 2?

Question

I want to be able to modify a part of the page of the details of the products of magento 2

The marked part is the one that I want to be able to edit, add or remove content is that section.

So far I can modify the title, the price and the description below, but how do I manage to manipulate that section? From the admin panel is the content section. I have tried so

public function afterLoad(\Magento\Catalog\Model\Product $subject, $result)
{
    $subject->setData('content', $subject->getContent() . '- TEST CONTENT');
    return $result;
}

But it does not work, how can I solve it?

And this is my di.xml file

<config>
  <type name="Magento\Catalog\Model\Product">
    <plugin name="change_product" type="Devchannel\HelloWorld\Plugin\Product " sortOrder="1" disabled="false"/>
  </type>
</config>