How to force stylesheet to load before anything else in header?

The tag that you want to call to execute your function is the wp_head() with a priority of 1.

In your child theme’s functions.php file, add the following:

add_action( 'wp_head', 'wpse_239006_style', 1 );
function wpse_239006_style() {
    wp_enqueue_script();
}