See HABot Walkthrough (1/n): Introduction and Installation for a start. I’m sure there is even more stuff. The great thing once you have a model is there are all sorts of ways you can use it.
That has never been part of openHAB itself. That log viewer is Frontail and openHABian comes with it installed and configured to follow openHAB’s logs. What I don’t know yet (haven’t had time to play with OH 3 yet) is whether there is a way to add Frontail to the new UI like you could add a new tile to the old dashboard.