How to Crop a PDF using C#. For further details: https://kb.conholdate.com/total/net/how-to-crop-a-pdf-using-csharp/

how-to-crop-a-pdf-using-csharp.cs

static void Main(string[] args) // Crop a PDF page in C#
{
    // Set the license
    new Aspose.Pdf.License().SetLicense("Aspose.Total.lic");

    Aspose.Pdf.Document pdfDoc = new Aspose.Pdf.Document("ImageAndText.pdf");
    System.Console.WriteLine(pdfDoc.Pages[1].CropBox);
    System.Console.WriteLine(pdfDoc.Pages[1].TrimBox);
    System.Console.WriteLine(pdfDoc.Pages[1].ArtBox);
    System.Console.WriteLine(pdfDoc.Pages[1].BleedBox);
    System.Console.WriteLine(pdfDoc.Pages[1].MediaBox);

    // Create a new Box Rectangle
    Aspose.Pdf.Rectangle rect = new Aspose.Pdf.Rectangle(190, 210, 2060, 1430);
    pdfDoc.Pages[1].CropBox = rect;
    pdfDoc.Pages[1].TrimBox = rect;
    pdfDoc.Pages[1].ArtBox = rect;
    pdfDoc.Pages[1].BleedBox = rect;

    pdfDoc.Save("cropped_modified.pdf");
}