Convert html to pdf using command prompt in console app.

To my knowledge, there is no direct way to do this using the default Microsoft .NET classes. Therefore, you will need to use .NET classes from a programming toolkit (like LEADTOOLS) that supports this type of conversion.
You can use LEADTOOLS DocumentConverter class to convert your HTML (and other document or image files) to PDF. You can find more details here:
https://www.leadtools.com/help/leadtools/v19/dh/doxc/leadtools.documents.converters~leadtools.documents.converters.documentconverter.html

The code will be something as follows:
+----------------------+
public void DocumentConverterExample()
{
using (DocumentConverter documentConverter = new DocumentConverter())
{
var inFile = Path.Combine(ImagesPath.Path, @"input.htm);
var outFile = Path.Combine(ImagesPath.Path, @"output.pdf");
var format = DocumentFormat.Pdf;
var jobData = DocumentConverterJobs.CreateJobData(inFile, outFile, format);
jobData.JobName = "conversion job";
var job = documentConverter.Jobs.CreateJob(jobData);
documentConverter.Jobs.RunJob(job);

if (job.Status == DocumentConverterJobStatus.Success)
{
Console.WriteLine("Success");
}
else
{
Console.WriteLine("{0} Errors", job.Status);
}
}
}
+----------------------+

Disclaimer: I am an employee of this library