Which messaging app are you using? I can say that with Messages, we have Chat features on a Pixel 4XL, a Pixel 3a, and a Pixel 5. So I see no reason why a Pixel 4a would not have Chat features using Google Messages. I can't say for sure if you would have those features using Message +
Scott5337 asks an excellent question. Which messaging app or service are you using? If you're talking about a different type of chat feature, just let us know.