There are social media that almost only have messaging (e.g. in my country everyone has Whatsapp) but I think the problem is once you give a kid a smartphone, i

There are social media that almost only have messaging (e.g. in my country everyone has Whatsapp) but I think the problem is once you give a kid a smartphone, it's going to be enormously difficult to effective control what they use. Most social media have web versions, you don't even need to install anything, and good luck putting some web filter once the kid is outside the home connecting to some WiFi... For similar reasons, legal age limits on social media wouldn't be very effective - age limits on smartphones probably would.