Scheduling the phone to automatically switch off at certain times (for example, every three hours) can be helpful if a Cellebrite or Greykey machine isn't available right after the smartphone is seized.
Discussion
This is a GrapheneOS feature by default, 18 hours but configurable to 30 minutes of inactivity. iOS implemented it too but it's done in 3 days of no unlock. The Shortcuts app could be useful for this as you can assign device restarts to a trigger. A more primitive shortcut could be to assign a reboot when the clock hits a certain hour such as when you're asleep.
Stronger USB port security features would help, I don't see why Apple couldn't copy what GrapheneOS does with disabling Pixels' USB-C port at a hardware level when they create both the phone and OS.
If there were still phones with removable batteries that could be charged outside the device, it would open up a lot of possibilities. Just a little soldering could permanently disable the USB port.
They should still need the feature. Forensic experts would be trained in device repair and just replace the port, so it should disable itself even when the port is replaced. It would increase the time before an extraction attempt could be performed though.
Fixing the door would require the phone to be turned off and put into BFU mode.