Trip to the USA and the requirement to show social media

I plan to visit the USA as a tourist and have read that now, to obtain entry permission, I might be required to provide my social media history for the past 5 years. I'm interested in whether this is indeed a mandatory requirement for such travelers, what documents need to be prepared, and whether I can be denied entry due to some posts or content on social media? What other nuances should I pay attention to when preparing for such a trip?