“Unprecedented,” the highly anticipated documentary from British filmmaker Alex Holder, is more about Trump family dynamics than the attempted coup on the Capitol. The three-part documentary, which premiered Sunday on Discovery+, has been on calendars since the Jan. 6 committee subpoenaed Holder in late June, asking for the raw footage he and his team filmed on the day of the insurrection, as well as footage of interviews with former President Donald Trump; former Vice President Mike Pence; Trump’s eldest children, Donald Trump Jr., Ivanka and Eric; and Ivanka’s husband, Jared Kushner. But the…