Set Default Product Type to Variable in WooCommerce https://wpsites.net/?p=114472

default-product-type

function set_default_product_type_variable() {
    ?>
    <script type="text/javascript">
        jQuery(document).ready(function($) {
            // Set the default product type to "variable"
            $('#product-type').val('variable').change();
        });
    </script>
    <?php
}

add_action('admin_footer', 'set_default_product_type_variable');