Once Autopilot is engaged you can do what you like - look at the countryside, have a snack, engage in a phone conversation, read Miscellany..........
To quote
Tesla:
Do I still need to pay attention while using Autopilot?
Yes. Autopilot is a hands-on driver assistance system that is intended to be used only with a fully attentive driver. It does not turn a Tesla into a self-driving car nor does it make a car autonomous.
