iPad iOS 13 Hacked

The observations you have do not correspond with a hacked iPad.

A hacker would usually try to covertly monetize your iPad somehow, for example by using it for cryptocurrency mining, by extracting data for later ransoming, grab social media logins, payment information or similar. In case of a targeted attack, the hacker could be after sensor data such as audio from the microphones or video from the cameras, or after documents and similar data.

The main word here is covertly. A hacker would see no benefit from highlighting random words on your screen or typing jibberish.

When you have fully erased all content & settings from the iPad, it wouldn't have network connectivity immediately, and you state that the problems persist during the setup process.

These thing seems to indicate that you are not dealing with a hacker.

I would consider other possibilities: Mainly that you have a broken digitizer (i.e. the touch screen picks up touches that haven't been made). I would call Apple or the place you've bought the iPad to arrange for repairs.

As the problem persists after a full "erase all contents & settings", I doubt that the problem is related to Accessibility settings or peripherals such as keyboard covers or Bluetooth keyboards - but it is worth checking those as well.