gb-filter-query-block.php

<?php
add_filter( 'generateblocks_query_loop_args', function( $query_args, $attributes ) {
    // Add a custom class to the "grid" item. Need to double check and see if that's still the case for GB 2.0
    if ( ! empty( $attributes['className'] ) && strpos( $attributes['className'], 'custom-class-here' ) !== false ) {

        $custom_args = array(
          // list of custom arguments
          'orderby' => 'title',
          'order' => 'ASC'
        );
        return array_merge( $query_args, $custom_args );
    }
    return $query_args;
}, 10, 2 );