How to get a rendered output field from view object programatically
Use the following code.

foreach ($view-&gt;result as $row) {
  // Change the full view with your view mode.
  $render_array = $row-&gt;_entity-&gt;field_slider_banner-&gt;view('full');
  $field_slider_banner_markup = \Drupal::service('renderer')-&gt;renderRoot($render_array);
}


Alternatively, you can use the following code. 

foreach ($view-&gt;result as $id =&gt; $row) {
  $my_field_value = $view-&gt;style_plugin-&gt;getFieldValue($id, 'field_name');
}