BRUSSELS, July 13 – The European Union will move to limit young children's access to social media across the 27-member bloc, European Commission President Ursula von der Leyen said on Monday, in what would be the biggest such effort to date to guard against online dangers.Von der Leyen presented a paper from two experts recommending a tiered approach, with under-13s only allowed to use social media for limited periods under the supervision of parents, caregivers and teachers. The curbs would be lifted gradually as teenagers got older."It is clear we need age-appropriate restrictions to platforms," von der Leyen told reporters…