In practical terms, I think the only way to force social media platforms to be more pro-active in stopping abuse is for people, the media and organisations to stop using them. A user strike would grab the attention of these companies pretty quickly. It would affect their reputation, their advertising, their revenue and their share prices. I don't see how laws in one or a few countries would have the same impact. It's a global business and difficult to control.
Sadly, I suspect racism is endemic, not just in the UK but worldwide. Time and education can be helpful but there are those who cling to their stereotypes and enjoy abusing people. It is illegal. Identify and prosecute is the normal course so social media should not be an exception.
Football supporters are like most large groups of people; the good, the bad and the ugly. Sadly, when aroused, the extremes are more audible and visible.