The Supreme Court has already expanded President Donald Trump’s authority in a string of emergency rulings, but he’s signaling in his firing of Federal Reserve governor Lisa Cook and other issues likely headed to the court that he continues to seek broader powers for the executive branch. The cases could serve as major tests of how much further the nation’s high court is willing to go to bless the president’s assertion of executive authority. They differ from previous showdowns because of the sheer magnitude of the authority Trump is seeking to wield and because he wants greater control over powers...