I’d start playing around with eugenics. Selecting for intelligence, strength, etc. Really see how far you could push humans as a species in just a few generations.

Also, child developmental experiments would be huge. There’s that one study that tried to see if raising a boy and a chimp at the same time would lead to the chimp acting human. It was stopped because the boy started acting like a chimp instead. What if it had continued?

If everything is being perfectly simulated, most things would still be unethical.

Computer, determine how many licks it takes to get to the center of a Tootsie pop and if any owls try to interfere with the experiment kill them on sight.