How do I prevent my M2 MacBook Air from automatically starting up when I open the lid?

Not possible is the short answer

Apple has designed newer computers like the M2 MacBook AIR to auto startup when the lid is opened even the smallest amount.

The best you could do, is Shutdown the computer totally and leave the Lid Up.

I use this method on the same machine when attempting to Clean the Screen 😎

Does not have to be totally Open

Just be sure nothing at all every touches the keyboard as that will activate the Auto Startup Process

Should that not be acceptable

 Product Feedback - Apple and make it known to Apple regarding this ongoing issue 

Welcome

This maybe not as important to some but is to me.

The Auto Boot with Lid Opened could be a good thing should the computer be misplaced or stolen, yes stolen

With Find My enabled, the moment the thief opens the computer you could be able to Track the device

Set up the Find My app to locate a missing Mac, device, or item

The small in convince seems to out weight this

mrmagnetoman88 wrote:

Ah, I wasn't aware that opening the lid of a MacBook would render it discoverable through the 'Find My Mac' feature. Yes, that's a pretty wise feature to introduce, although, if I may say, I still prefer being given the option of disabling certain features on one's own accord. For example, the way one has the option of turning passcode off on his or her iPhone, in spite of him or her doing so at his or her own peril. Just my two cents!

Not to flippant really

There are times where having " certain options " needs to weighted against the downside, lost to stolen expensive pieces of equipment

It would be very difficult to clean the keyboard / screen or passcode-less iDevices would be impossible if it were lost / stolen.

Just shut the mac down before you clean it - Apple menu->Shut Down.

And how often do you do this, anyway?