It's worth pointing out that if you would like to immediately require authorisation for USB accessories, you can do the same trick that disables Face ID and Touch ID temporaily: simply hold down the side buttons until the "Slide to power off" screen appears.
As a concession to user convenience, the restrictions on the Lightning port only comes into effect if the Lightning port is not now being used, and the device has not been unlocked for more than a hour. This means if you haven't turned the USB Accessories toggle on, and it has been more than an hour since your Apple device was locked, a USB accessory won't be able to communicate with your device. Once an iPhone has been locked, a countdown begins before USB Restricted Mode activates.
Of course, this only works if the device hadn't entered in USB Restricted Mode by the time the police obtained it. "In other words, we have found no obvious way to break USB Restricted Mode once it is already engaged". While iOS 11.4.1 is likely the final update before iOS 12, this bug could force Apple to push out 11.4.2 quickly.
However, if you aren't actually happy with the release, and you want to go back to an earlier version of iOS, then be aware that Apple is now only signing iOS 11.4, which means that you will only be able to downgrade to iOS 11.4.
iOS 11.4.1 includes bug fixes and improves the security of your iPhone or iPad. "The ability to postpone USB Restricted Mode by connecting the iPhone to an untrusted USB accessory is probably nothing more than an oversight", Afonin admits.
Based on Apple's previous update cycles, it is possible that these are the last updates for these operating systems before iOS 12 and its cousins arrive later this year.