You don't get a blue bubble for using RCS. That's still reserved for iMessage exclusively. (At least, on iOS 26 in the US on T-Mobile)

Yeah, there's a myth spread on the internet after Apple announced rcs support in iMessage that it was the end of green bubbles for android users. But green bubbles still exist; they never meant the other party is just using sms, they meant the other party isn't using iMessage.