Filter the query on the events archive to only show upcoming events

filter_archive_query.php

function show_upcoming_events( $query ) {
    
    if( is_admin() ) {
        return $query;
    }

    if ( ( isset($query->query_vars['post_type']) && $query->query_vars['post_type'] == 'event' ) ) {

        $today = date('Y-m-d H:i:s', strtotime("-1 days"));
        $meta_query = array(
            array(
                'key'         => 'date',
                'compare'     => '>',
                'value'       => $today,
                'type'        => 'DATETIME'
            )
        );
        
        $query->set('meta_query', $meta_query);
        $query->set('order', 'ASC');
        $query->set('orderby', 'meta_value');
        $query->set('meta_key', 'date');
        $query->set('meta_type', 'DATETIME');
        
    };
    
    // return
    return $query;

}