Append a random string to WordPress static assets, to bust a cache, if you are not on a production server.

functions.php

function prefix_enqueued_assets() {

	$version_string = NULL;

	if ( 'production' !== wp_get_environment_type() ) {
		$version_string = bin2hex(random_bytes(4));
	}

	wp_register_style(
		'prefix-theme-css',
		get_stylesheet_directory_uri() . 'style.css',
		array(),
		$version_string
	);

	wp_enqueue_style( 'prefix-theme-css' );

}

add_action( 'wp_enqueue_scripts', 'prefix_enqueued_assets' );