I've traveled a lot internationally and SMS is a US/Australia phenomenon, otherwise it's dead. Coincidentally those countries have a very high iOS market share, so it's actually iMessage in most cases, which makes the traditional SMS even more dead.RCS is not SMS like, but it can fall back to SMS - the world surely hasn’t moved on, only Europe, and only because they trust Meta to be the arbiter of all of their messaging…which is definitely not a basket I’d put my eggs in.
The specific app differs per region, for example in Europe, India and South America you'd use WhatsApp, in Russia you'd use Telegram, in China you'd use WeChat etc.
The only SMS I receive are automated messages from companies.