Warning: spoilers for the TV show Designated Survivor ahead.
The American TV drama Designated Survivor is set in a hypothetical world where terrorists have successfully attacked the State of the Union address and killed nearly all of the senior members of the US government. Many early episodes have plot points centering around Constitutional issues and Presidential powers that Americans will remember from their school days (e.g. the ability of the President to federalize units of the National Guard). Based on those early episodes, it's clear the show is attempting to be accurate in its depiction of existing US law, and not just making stuff up wildly or in an alternate reality with different laws.
In S1E11 of the show, police officers have surrounded a building where they believe a terrorist is hiding. They are on US soil, and believe that the occupant of the building is the person who attempted to assassinate the president several hours earlier. It is unclear if they know the nationality/citizenship status of the terrorist.
The (Acting) President of the United States has an open line of communication to the on-scene police commander from a bunker in the White House. Other characters explain that standard procedure is for police to attempt to take the alleged terrorist into custody so that criminal charges may be brought, and for police to not fire their weapons unless attacked. The President gives a preemptive order for police to kill the suspect even if a non-lethal option is available. His advisors object, but he overrules them, explicitly commanding them to "shoot to kill."
The show set things up to feel sort of like a Commander-in-Chief giving orders to a military unit in a war zone overseas, but ultimately, the scenario was a domestic police operation. So, is this something a President can actually do, from a legal standpoint? Or did the show decide to ignore reality in the service of the plot this time?