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:

When RCS messaging became available on the iPhone with the rollout of iOS 18, the technical director of the GSM Association teased that the next major milestone for the messaging standard is the addition of interoperable end-to-end encryption.

The GSMA has announced that the latest specifications for RCS include support for end-to-end encryption using the MLS (message layer security) protocol. This is great news for a sizeable chunk of users in North America,