In the days before he left office, President Donald Trump instructed that his family get the best security available in the world for the next six months, at no cost — the protection of the U.S. Secret Service. According to three people briefed on the plan, Trump issued a directive to extend post-presidency Secret Service protection to his four adult children and two of their spouses, who were not automatically entitled to receive it. Trump also directed that three key officials leaving government continue to receive the protection for six months: former treasury secretary Steven Mnuchin, former chief of staff...