Arizona: A Donald Trump Jr. event is full of people and conspiracy theories.

CHANDLER, Ariz. — More than 800 people lined up early on Tuesday morning to see Donald Trump Jr., the president’s eldest son, and Charlie Kirk, the 26-year-old founder of Turning Point USA, speak at a hotel here.

The queue was dotted by red “Make America Great Again” hats. Some people wore T-shirts supporting the QAnon conspiracy theory or with slogans like “Don’t California My Arizona.”

Inside, around 500 chairs were lined up as tightly as airplane seats. When those filled up, hundreds more people crammed in, standing shoulder to shoulder. When the ballroom could hold no more, organizers swung open its double doors and urged attendees to just keep squeezing in. Only a handful wore masks.

One man made the sign of the cross as he entered.

“This room only held 500; we probably squeezed 800 or 900 in there,” said Tyler Bower, one of the organizers of the event, part of the Students for Trump group’s “Four More Tour.”

People here might have been less worried about catching the coronavirus than the prospect that the president could lose Arizona, a once solidly conservative state where most polls have shown him trailing Mr. Biden. And if the reaction of the crowd was any indication, they were most worried about claims of child sex trafficking being imported to Arizona from California.

Onstage, Mr. Kirk, the younger Mr. Trump and his girlfriend, Kimberly Guilfoyle, offered up red meat to the crowd, much of it wildly exaggerated or without basis in fact. They complained about the persecution of conservatives, bantered about the “96 genders” that they said Democrats now recognized, suggested that Mr. Biden has dementia, and claimed that Osama bin Laden had once endorsed Mr. Biden.

But the event reached its peak as the three speakers took up the bogus conspiracy theory that Democrats condone pedophilia, They also took on “Cuties,” a French film released on Netflix that depicts preteen girls in a provocative dance crew, and that critics say hypersexualizes young girls.

“You know what the left is doing? They’re justifying ‘Cuties,’ they’re justifying pedophilia,” Mr. Trump said, pointing to a recently passed law in California that aims to end discrimination against L.G.B.T.Q. young adults in statutory rape convictions. Conspiracy theorists associated with the QAnon movement have claimed that the law favors pedophiles, which it does not.

But the idea that the president is combating pedophilia, which is central to the QAnon theory, buoyed many in the crowd. “To me, the part that got our cheeks flushed and tingling was when everyone in the room stood up to applaud saving our children,” said one woman, who declined to give her name.

Not all of those in attendance were energized by the arguments.

Jonathan Gross, an 18-year-old Republican and finance student from Tucson, was one of the few wearing a mask inside the event. He said he had hoped to hear about the president’s policies and was disappointed to see that it was just a live trolling session.

He described the Trump re-election campaign as having the maturity level of a teenager.

“They were just throwing out a bunch of stuff, saying Joe Biden is basically brain-dead for having to read off a teleprompter, calling the left sheep, and that ‘Cuties’ argument,” he said. “I came to hear about what Trump is planning to do with his re-election, but it felt like just slander of the left.”