Cynically, I think they're trying to imitate fascist - sorry, "alt right" - movements from the past, which typically did involve a lot of shows of force to intimidate other political entities into standing down and / or forfeiting the democratic transfer of power in some way. For instance, Mussolini used his movement to menace the monarchy into recognising him as a ruler during the March on Rome. Like, it's vastly more complicated than that but I don't think these people really go in for "complicated."

Specifically citing the Wikipedia page (lol),

The King then handed over power to Mussolini (who stayed in his headquarters in Milan during the talks) by asking him to form a new government. The King's controversial decision has been explained by historians as a combination of delusions and fears; Mussolini enjoyed wide support in the military and among the industrial and agrarian elites, while the King and the conservative establishment were afraid of a possible civil war and ultimately thought they could use Mussolini to restore law and order in the country, but failed to foresee the danger of a totalitarian evolution.

And that sounds a lot like what's going on, y'know? It's just, like, what higher authority do they think they're menacing in fucking Brazil?

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Generously, I think some of them believe they're protesting, and like, theoretically if a bunch of pissed off lesbians wanted to protest at the capital for the creation of LGBT-specific homeless services or if BLM wanted to protest at the capital to demand that police funding be repurposed toward the creation of social workers as first responders to mental health calls, I'd be like, yea, cool. But of course queer and black activists tend to know that protesting by murdering a bunch of cops and smearing your shit on the walls isn't exactly a worthwhile move.