Documentaries about the American political system are legion, and grow every week. You can bet we’ll be seeing dozens more by the time this year’s presidential election rolls around. But “Boys State” (Apple TV+), the 2020 documentary directed by Amanda McBaine and Jesse Moss, came at government from a different and very refreshing angle. That film chronicles a few participants in the Boys State program run by the American Legion in Texas and every other state except Hawaii. It’s an immersive mock government approach, designed to give rising high school seniors a taste of campaigns, diplomacy and the structure of American government.