Indeed. Currently using an Android 13 Motorola until my Sony is fixed. It's not labeled RCS, but one of the first things I did was disable Messages Settings ->

Indeed. Currently using an Android 13 Motorola until my Sony is fixed. It's not labeled RCS, but one of the first things I did was disable Messages Settings -> Chat Features -> Enable chat features - Use WiFi or data for messaging when available ...which disabled a bunch of other things. While I don't recall what appeared originally, the Send button for messages is labeled either SMS or MMS, so I suppose that did the trick. No nagging. I did just find and disable the RCS Config Service, too, and testing that everything still works.