Usually you actually need to not use third party apps. RCS on Android is usually restricted to Google Messages (or maybe Samsungs built in messages app). Everyone else got the boot

You also sometimes have to enable in the settings for Android Messages (and have a supported carrier). iMessage also has an option to enable RCS but I believe its on by default in the newer versions of iOS

Hmm ok so it doesn't actually work :(

Even if it worked with 3rd party apps, at that point why not install something like Signal.

I don't know, I haven't used Android in quite a few years, but it was my understanding that it was in Google's default SMS app. When I got iOS 18, all of my texts to Android users switched automatically to RCS, so they didn't have to do anything.

I wrote an "SMS" to the previous tenant of my new flat recently and it got seamlessly upgraded to rcs. With me on an android and them on an iPhone. This was using Google messages, which was the default on my zenfone for sms

My friend group chat was suddenly RCS after updating iOS today and it’s great - no more “So and so liked ‘the entire message body’” messages, we all just see the thumbs up reaction