Question: When MacBook Pro 2018 is completely shut down, it will power up by simply opening the lid, pressing any key, or tapping the trackpad, which is very annoying. I managed to make it not power up when the lid is lifted, but I couldn't figure out how to prevent the key presses or trackpad tap from doing so.

Answer: 
The Mac *is* shutting down and powering off, but newer Mac's include a feature that powers on when *any* key is pressed or the touch pad is touched.

If you need to stop this behavior--to clean the keyboard, for example--you can force a shutdown once.

Press and hold the **left** `Control` and `Command` buttons with the **right** `Shift` button for a total of 7 seconds. Without releasing them, press the Power button and hold them all together for an additional 7 seconds. Your Mac can only be powered on by using the Power button.

Unfortunately, there is no way to disable this permanently.
Short answer: you can't

**MacBook Pro 2018 with Catalina 10.15.7**

My experience is similar to Billie Hawkin's excellent answer above: setting AutoBoot to %00 prevents boot on lid open

However, `sudo shutdown -h now` did not, in my experience, prevent the behavior. When any key is pressed, the laptop still booted up.

What do service shops do? crack open the case and pull the battery!?

And Apple Support was no help :P