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

The new specifications will use RCS Universal Profile 3.0, a cross-platform encryption protocol that will make it easier for iPhones and Android devices to identify each other. The profile allows for richer deep linking,