Based on https://en.wikipedia.org/wiki/Rich_Communication_Services, it looks like Claro should support RCS (still branded as "joyn" though, so could be an outdated version of the spec).

I don't think carriers had much of a reason to invest in RCS servers up till recently, because only Android really supported it and that came with a free, third party server. Maybe now carriers will start caring.

By online statistics, Brazil seems to be a WhatsApp country, though, so I don't think many people will be using carrier services for chat. In turn, I don't think carriers will be quick to invest in servers and software to provide RCS to customers very soon.