Hey, so I've encountered something fairly new on my Moto G5 plus.
My boyfriend has a Samsung Galaxy Note 8, and he's with Sprint. On my G5, I can see when he has read my texts, and I can even see when he's typing. This feature is totally unique to him- I've looked at texts between myself and others, some of whom have iPhones, the S7, etc. My text simply shows as SMS with others, as opposed to "Delivered" or "Read" with my boyfriend.
I think it's pretty cool, but what's up with it? There don't seem to be any clear answers online that I can find.
I think what you are referring to is a feature called "enhanced messaging" and it depends on the messaging app. Most have it, some don't. It also has to be enabled on both phones in the text to get the extra features.
As previously states by User129too, this refers to the "Enhanced Messaging" functionality, also called "Rich Communications" or "Messages+" on other phone models. You can find more information about that at the following link, https://www.digitaltrends.com/mobile/what-is-rcs-messaging/. This is an external source, but it actually offers very useful information about the Enhanced Messaging feature.
We hope this helps.