Which is why phones should have duress passcode capability but that's another rant.

They do to some extent.

Holding the side button + volume button together until you see the power-off slider also temporarily disables Face ID / Touch ID, requiring the device passcode for unlocking.

You can also set your phone to erase after ten failed passcodes.

What exactly do you think the wrench-holder would do upon discovering the use of this?

stop hitting you with the wrench as it is no longer a useful option

Because people willing to hit you with a wrench to recover a password are definitely going to stop when they discover that you actually destroyed the thing they were looking for, thus "getting one over" on them...

Although to be fair, they might just switch to a pistol at that point. After all, you are no longer useful once the data has gone.