This is a simple snippet that will allow you to move the Related Products from below the tabs to inside the single product tabs, in a brand new tab.

PHP Snippet: Move Related Products to a Tab – WooCommerce Single Product Page
/**
* @snippet Related Products in a New Product Tab - WooCommerce
* @how-to Get CustomizeWoo.com FREE
* @author Rodolfo Melogli
* @compatible WooCommerce 7
* @donate $9 https://businessbloomer.com/bloomer-armada/
*/
// First, let's remove related products from their original position
remove_action( 'woocommerce_after_single_product_summary', 'woocommerce_output_related_products', 20);
// Second, let's add a new tab
add_filter( 'woocommerce_product_tabs', 'bbloomer_new_product_tab' );
function bbloomer_new_product_tab( $tabs ) {
$tabs['related_products'] = array(
'title' => __( 'Try it with', 'woocommerce' ),
'priority' => 50,
'callback' => 'bbloomer_new_product_tab_content'
);
return $tabs;
}
// Third, let's put the related products inside
function bbloomer_new_product_tab_content() {
woocommerce_output_related_products();
}