https://www.howtogeek.com/how-to-send-rcs-messages-from-an-ipad/
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RCS is now available on Apple devices like the iPhone and iPad, but you’ll need to install the latest iOS 18 operating system first.
To verify RCS support for your carrier on your iPhone, open Settings > General > About > scroll to Physical SIM and tap Carrier until it changes to IMS Status and look for “Voice, SMS & RCS.”
To use RCS messaging on an iPad, set up Message Forwarding by logging into the iPad and iPhone with your Apple Account, open Settings > Apps > Messages > Text Message Forwarding and toggle on forwarding for the iPad
Sending and receiving text messages on an iPad isn’t particularly difficult, but there’s more than one kind of message format. If you want to send RCS messages from Apple’s tablet, you can do so as long as you set everything up correctly. Here’s how.
What Is RCS?
RCS is shorthand for “Rich Communication Services” and the short explanation is that it’s what’s been steadily replacing SMS messaging across a number of cell carriers. It still lets you send text messages, photos, videos, and so on to other people and other devices. But it also boasts better quality for media attachments along plus perks like optional read receipts, being able to see when the other person is typing, and so on.
If this sounds a lot like Apple’s iMessage texting service that’s been a big part of the iPhone and iPad for years, that’s because they are functionally very similar. What makes iMessage different is that it’s proprietary for Apple devices only, and it allows for end-to-end encryption for texts (though RCS messages sent between users via Google Messages are also encrypted(.
All that being said, Apple did finally embrace (or at least allow) RCS messaging on the iPhone by way of its iOS 18 operating system update. This doesn’t mean you can effortlessly send RCS messages on your iPad yet, though.