Did you change the default reboot after 18 hours option?
Did you change the default USB-C behavior to "ON'?
Is it a serious national security investigation where the results aren't charges but drone strikes and rendition teams?
If the answer to those is no then you have essentially nothing to worry about and there is basically a zero percent chance they crack your phone via technical means (as opposed to learning your PIN somehow).
Unless they can unlock your phone within 18 hours it will reboot and be BFU.
Unless you changed the USB settings then, again it will have to reboot before they can establish a USB connection.
Unless it is a major NatSec investigation no one is potentially burning theoretical GOS exploits to get into your phone. Or the resources needed to try the more esoteric means of potentially cracking it.