How to select the first specific element after a element (not in) by using JS

Recently, I am working on a Youtube comment loader project, and I want to select the first <p> element after <a> element in this example:

<p></p>
<a id="this_is_the_a_element">
  <p></p>
</a>
<pre></pre> <!-- More random elements here -->
<p id="first_p_after_a"></p>
<p id="second_p_after_a"></p>
<p id="third_p_after_a"></p>

I know I can using substring to achieve that, but is there a more efficient way (just like querySelector) to do that?

Also, how could I select the second, third, and so on element after a specific element?