Enqueue any style sheet with a conditional comment (usually for IE)

functions.php

<?php

add_action( 'wp_enqueue_scripts', 'prefix_add_ie8_style_sheet', 200 );
/**
 * Enqueue an IE-specific style sheet.
 *
 * Add a style sheet for everyone, then mark it as conditional to IE8 or below.
 *
 * @author Gary Jones
 * @link   https://garyjones.io/enqueued-style-sheet-extras#ie
 */
function prefix_add_ie8_style_sheet() {
	global $wp_styles;

	wp_enqueue_style( 'child-ie8', get_stylesheet_directory_uri() . '/style-ie8.css', [], '1.0.0' );
	$wp_styles->add_data( 'child-ie8', 'conditional', 'lte IE 8' );
}