there are private exploits built into devices like Cellebrite that the police have access to. The system isn't as infallible as you think. Would not be surprised if the NSA and various hacking groups have stockpiles, too.

The iPhone has two main security systems to counter this, one being lockdown mode which disables USB data while the device is locked, and the other is the iPhone will reboot itself if it hasn't been unlocked for long enough. This puts the device in Before First Unlock state where the encryption keys are wiped from memory. This means no software bug can unlock the device because the encryption keys are derived from the users password.

The main attack left is brute forcing the lock screen password and bypassing the cooldown timer. This seems to be the method most used for getting access to phones. This is defeated by having an actual text password rather than the 6 digit password.

So yes they have advanced hacking tech, but the iphone security is remarkably effective and as a user there are a couple of simple measures that make it pretty much unbreakable.

If you believe you are at risk of having your phone taken and plugged in to a Cellebrite like device, enable Lockdown Mode, set a good password and if possible hit the power button 5 times to disable face id.