Apple dropped the iOS 26.5 release candidate for developers, which at this point means the public build is days away. A week at most.
The changelog confirms what had been circulating in rumors: RCS messaging on iPhone is getting end-to-end encryption. But don’t update and immediately expect anything to change in your Messages app. Apple’s own notes flag it as launching in beta, available only through “supported carriers,” rolling out gradually rather than switching on for everyone at once.

So, depending on who your carrier is, you might sit on 26.5 for a while before the feature actually shows up.
When it does fully land, the bigger picture is this — iPhone and Android users texting over RCS will have encrypted conversations for the first time. iMessage has had E2E encryption for years, but cross-platform messaging always meant dropping to unencrypted RCS. That gap is finally getting closed, just not overnight.