No, you hang up!
Things are changing, and even before texting there was the issue of "ending" a conversation. Someone can always have the last word.
I have found that the iMessage feature to tag a post with a thumbs up/down, heart, haha, etc, is actually perfect for this. Someone makes what seems like the final comment and you "thumb up" it. There is no real response to that.
Whereas if you say "Thanks" and close the app/window, they may pop up again with a "Thank you too" or "No problem", etc.
But the idea of a "thumbs up" like this does not really fit previous normal language. People don't really do that in real life, or if they do they seem strange (even if that does end the conversation).
Even so, I find myself at a loss when using a different app that does not have that feature.
So we are all stumbling in the dark working out the new etiquette and language. It is exciting times.