add_action('post_grid_main', 'post_grid_main_20200614', 10);

function post_grid_main_20200614( $atts){

    $grid_id = $atts['id'];
    $post_grid_options = get_post_meta( $grid_id, 'post_grid_meta_options', true );


    ?>
    <div class="">Custom HTML here</div>
    <?php
}

 

 

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