Android unfortunately doesn't have anything like this enabled by default, and what it allows you to enable is much more limited.
Lockdown mode[0] has to be enabled manually (it's hidden deep in setting that most people won't notice), and all it does is add an additional soft button when you long-press the power button. That button will disable biometric unlocking and hide notifications, but only until the phone is next unlocked.
Unfortunately, in situations where you might want to use this, long-pressing the button and then having to tap the screen is cumbersome.
To be fair, the third button is the power button, which will turn off the device and is effectively another way of disabling the biometric unlocking. So if you randomly press the top of the screen, you have a 2/3 chance of locking your phone as desired... and a 1/3 chance of calling 911 instead (which may make the situation worse).
https://screenrant.com/android-lockdown-mode-purpose-enable-...
The original statement was
> most modern operating systems have built in features to quickly disable them on demand
A custom-made gesture using a third-party launcher is not built-in (to say nothing of whether that's accessible or feasible for the vast majority of Android users).
Most users would be okay with having these features only available through the Apple App Store.
Instead, the result is none of those features on their phone.
That's your particular phone. It does not apply to most Android phones.