Add custom text to the “thank you” page in WooCommerce

/**
 * Adds text to the "Order received" ("Thank you") page.
 *
 * @see https://wpcodebook.com/woocommerce-add-text-thank-you-page/
 * @see https://github.com/woocommerce/woocommerce/blob/9.3.3/plugins/woocommerce/templates/checkout/thankyou.php#L82
 */
add_action( 'woocommerce_thankyou', function ( $order_id ) {
	echo '<p>' .
		__( 'Delivery time: 7-10 business days.' ) .
	'</p>';
}, 11 );