Even government officials are now telling us to use End-to-End encryption. (We've come a long way since the Clipper Chip era.) Signal is a great tool that's free and works across all major platforms. If one's circle is primarily in the Apple ecosystem, iMessage and FaceTime (including FaceTime audio) are also end-to-end encrypted.
There are plenty of other options available. Including many enterprise-friendly solutions that can be used to meet data retention/compliance/etc requirements (i.e. data is encrypted between the clients and the service, but the service retains a copy). Just make sure to read the fine-print and check for any publicly available security research before committing to a product/solution.
https://www.linkedin.com/posts/jen-easterly_securing-your-communications-activity-7271582429260255233-OGMi?utm_source=share&utm_medium=member_desktop