A small plugin that enables tags on PDF files to create a simple press review archive using the theme's attachment archive template with a custom bulk action to add multiple files to that tag.

press-review-archive.php

<?php
/**
 * Press Review Archive
 *
 * @package     press-review-archive
 * @author      Bernhard Kau
 * @license     GPLv3
 *
 * @wordpress-plugin
 * Plugin Name: Press Review Archive
 * Plugin URI: https://kau-boys.de
 * Description: A small plugin that enables tags on PDF files to create a simple press review archive using the theme's attachment archive template
 * Version: 0.1
 * Author: Bernhard Kau
 * Author URI: https://kau-boys.de
 * License: GPLv3
 * License URI: http://www.gnu.org/licenses/gpl-3.0.txt
 */

/**
 * Enable tags on attachments
 */
function press_review_archive_register_taxonomy_for_object_type() {
	register_taxonomy_for_object_type( 'post_tag', 'attachment' );
}

add_action( 'init', 'press_review_archive_register_taxonomy_for_object_type' );

/**
 * Adds a rewrite rule for the press review archive
 */
function press_review_archive_add_rewrite_rule() {
	add_rewrite_rule(
		'^pressespiegel(?:/(\d{4}))?(?:/(\d{2}))?(?:/(\d{2}))?/?',
		'index.php?tag=pressespiegel&year=$matches[1]&monthnum=$matches[2]&day=$matches[3]',
		'top'
	);
}

add_action( 'init', 'press_review_archive_add_rewrite_rule' );

/**
 * Change the main query to show only PDF files on the press review archive
 *
 * @param WP_Query $query The main query.
 */
function press_review_archive_pre_get_posts( WP_Query $query ) {
	if ( is_press_review_archive() ) {
		$query->set( 'post_type', 'attachment' );
		$query->set( 'post_mime_type', 'application/pdf' );
		$query->set( 'post_status', 'inherit' );
	}
}

add_action( 'pre_get_posts', 'press_review_archive_pre_get_posts' );

/**
 * Set the archive title and remove thr prefix.
 *
 * @param string $title The archive title.
 *
 * @return string
 */
function press_review_archive_get_the_archive_title( $title ) {
	if ( is_press_review_archive() ) {
		$tag   = get_term_by( 'slug', 'pressespiegel', 'post_tag' );
		$title = $tag->name;
	}

	return $title;
}

add_filter( 'get_the_archive_title', 'press_review_archive_get_the_archive_title' );

/**
 * Set the post thumbnail to large size for the press review archive
 *
 * @param string $p The attachment HTML output.
 *
 * @return string
 */
function press_review_archive_prepend_attachment( $p ) {
	if ( is_press_review_archive() ) {
		$p = '<p class="attachment">';
		$p .= wp_get_attachment_link( 0, 'large', false );
		$p .= '</p>';
	}

	return $p;
}

add_filter( 'prepend_attachment', 'press_review_archive_prepend_attachment' );

/**
 * A helper function to test if the currently requested page is a press review archive pae
 *
 * @return bool
 */
function is_press_review_archive() {
	return is_archive() && is_tag( 'pressespiegel' );
}

/**
 * Adds a new option to the bulk actions of the media library.
 *
 * @param array $bulk_actions The bulk actions for the screen.
 *
 * @return mixed
 */
function press_review_archive_register_bulk_actions( $bulk_actions ) {
	$bulk_actions['press_review_archive'] = __( 'Add to press review', 'press-review-archive' );

	return $bulk_actions;
}

add_filter( 'bulk_actions-upload', 'press_review_archive_register_bulk_actions' );

/**
 * Add the selected elements to the press review archive tag
 *
 * @param string $redirect_to The redirect URL.
 * @param string $doaction    The action being taken.
 * @param array  $post_ids    The items to take the action on.
 *
 * @return string
 */
function press_review_archive_bulk_action_handler( $redirect_to, $doaction, $post_ids ) {
	if ( 'press_review_archive' !== $doaction ) {
		return $redirect_to;
	}

	$added_items = 0;

	foreach ( $post_ids as $post_id ) {
		$post = get_post( $post_id );

		if ( 'application/pdf' === $post->post_mime_type ) {
			$term_taxonomy_ids = wp_set_object_terms( $post_id, 'pressespiegel', 'post_tag', true );

			if ( ! is_wp_error( $term_taxonomy_ids ) ) {
				$added_items++;
			}
		}
	}

	$redirect_to = add_query_arg( 'press_review_archive_added', $added_items, $redirect_to );

	return $redirect_to;
}

add_filter( 'handle_bulk_actions-upload', 'press_review_archive_bulk_action_handler', 10, 3 );

/**
 * Adds a notice after the bulk action completed
 */
function press_review_archive_bulk_action_admin_notice() {
	if ( ! empty( $_REQUEST['press_review_archive_added'] ) ) {
		$items_added = intval( $_REQUEST['press_review_archive_added'] );
		printf( '<div id="message" class="updated fade"><p>' .
		        _n( 'Added %d file to the press review archive.',
			        'Added %d files to the press review archive.',
			        $items_added,
			        'press-review-archive'
		        ) . '</p></div>', $items_added );
	}
}

add_action( 'admin_notices', 'press_review_archive_bulk_action_admin_notice' );