It's up to the mobile networks to support that (usually by outsourcing it to Google, which I'm not sure they do for free).

It's weird it's taking that long, as RCS on Android have been supported for ages here, I think even before some US carriers.

I first tried RCS in early 2019.

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it looks like Claro should support RCS (still branded as "joyn" though, so could be an outdated version of the spec).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.