The GSMA published a blog post to announce the new features coming to RCS. The iPhone is getting end-to-end encryption RCS messages via the Messaging Layer Security (MLS) protocol:

Text messages sent between iPhones and Android devices will soon benefit from end-to-end encryption (E2EE), after the GSM Association yesterday published new specifications for th

Apple will, at long last, enabling end-to-end encryption for RCS messages, allowing iPhones and Android phones to text each other with the security encryption provides for the first time.