Rendering plain text instead of formatted data
I believe you can use check_markup to render the text in the specified format. In your example, you'd want to also save the format, something like:

$query = db_insert('my_table')
  -&gt;fields(array(
   'full_detail_text' =&gt; $form_state-&gt;getValue('english_copy_text')[value],
   'full_detail_format' =&gt; $form_state-&gt;getValue('english_copy_text')[format],
   'date' =&gt; REQUEST_TIME,
  ))
 -&gt;execute();


Then when you go to render it in the hook_views_pre_render

$rendered_markup  = check_markup($full_detail_text, $full_detail_format),


For more info,
 see:
 https://api.drupal.org/api/drupal/core%21modules%21filter%21filter.module/function/check_markup/8.3.x