Modify event archive query

modify-event-archive-query.php

<?php
/*
 * Modifies the view of categories.
 * Events will be shown from newest to latest in descending order.
 * Only works on event category views, won't work on month view, shouldn't impact non-event category views.
 * Plugins: The Events Calendar
 *
 * Author: Barry Hughes
 * Last updated: July 12, 2017
*/

function modify_event_archive_query( $query ) {
    $type = $query->get( 'eventDisplay' );
    $event_cat = $query->get( 'tribe_events_cat' );

    if ( empty( $type ) || 'month' === $type ) {
        return;
    }

    if ( empty( $event_cat ) ) {
        return;
    }

    if ( ! $query->is_main_query() ) {
        return;
    }

    $query->set( 'eventDisplay', 'custom' );
    $query->set( 'order', 'DESC' );
}

add_action( 'pre_get_posts', 'modify_event_archive_query', 5 );