wp_is_https_supported()

Source

File: wp-includes/https-detection.php

function wp_is_https_supported() {
	$https_detection_errors = get_option( 'https_detection_errors' );

	// If option has never been set by the Cron hook before, run it on-the-fly as fallback.
	if ( false === $https_detection_errors ) {
		wp_update_https_detection_errors();

		$https_detection_errors = get_option( 'https_detection_errors' );
	}

	// If there are no detection errors, HTTPS is supported.
	return empty( $https_detection_errors );
}