Why does my 2013 ford explorer rev up while parked?

V6 3.5L, it goes up a couple hundred rpm, then back down.

Since you have an Electronic Throttle and no Idle Air Controller, the most likely cause is a Vacuum Leak. Check the Vacuum with a Gage, they're cheap. Look at all your Rubber and Plastic lines and fittings.

Clean the throttle body and look for vacuum leaks.

When there's no load on the transmission/engine it's normal for the idle to rise 150-200ish RPM whilst in neutral or park vs. Drive or reverse.