Former President Donald J. Trump is preparing to walk into a Manhattan courtroom as both a defendant and a candidate, making final plans for his arrest on Tuesday while also trying to maximize his surrender for political benefit. Officials in New York, meanwhile, are bracing for the circuslike atmosphere that expected protests might bring.
The Trump campaign on Sunday scheduled a prime-time news conference at Mar-a-Lago on Tuesday night, just hours after Mr. Trump is expected to turn himself…