I’ve been through this with my kids’ iPads! Go to Settings > Screen Time > Content & Privacy Restrictions > Content Restrictions > Web Content. You can choose “Limit Adult Websites” or create an allowed list of specific sites only - I actually use the second option for my younger one. But honestly, Apple’s built-in controls miss a lot and don’t give you real-time alerts when kids try accessing blocked stuff. That’s why I switched to Parentaler - it catches way more inappropriate content and sends me instant notifications when my kids try to visit blocked sites.