In Drupal 7 I used
hook_views_pre_render() to update the image style for specific results. I'm trying to do the same for a view in Drupal 8 but I don't have the same options available in the field.
An example of the code I used before:
$view->result->field_field_image['rendered']['#image_style'] = 'image_style_name';
There's no longer a 'rendered' array, just an ImageItem object with the target_id, title, width and height.