get a user roles at various context / level

// at course level

$context = \context_course::instance($course->id);

// at system level

//$context = \context_system::instance();

// at category level
//$context = \context_coursecat::($cat->id);

$roles = get_user_roles($context, $user->id, '',  'c.contextlevel DESC');

// $roles will be array