Australia’s controversial new law barring under-16s from social media is one of the toughest crackdowns yet on platforms including Facebook and TikTok as governments worldwide grasp for ways to protect children from harmful content.The blanket ban, passed late Thursday night, establishes some of the most stringent internet usage restrictions outside of China and other non-democratic regimes and could provide impetus to other governments to act. From Florida and Texas to France and the UK, author...