Print in high quality

Trying to print generated text and qr code image, but it does in very low quality.

Have tried to change the graphics settings with no chance,
attached an image how the text and the image are appears in PDF after printing.

private void doc_PrintPage(object sender, System.Drawing.Printing.PrintPageEventArgs e){
    var xheight = 726;
    var xwidth = 363;
    Bitmap flag = new Bitmap(xwidth, xheight);
    
    Graphics flagGraphics = Graphics.FromImage(flag);
    flag.SetResolution(300, 300);
    
    flagGraphics.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
    flagGraphics.TextRenderingHint = System.Drawing.Text.TextRenderingHint.ClearTypeGridFit;
    flagGraphics.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
    flagGraphics.PixelOffsetMode = PixelOffsetMode.HighQuality;

    flagGraphics.Flush();

    System.Drawing.Font font1 = new System.Drawing.Font("Tahoma",35, FontStyle.Bold, GraphicsUnit.Point);
    System.Drawing.Font fontjob = new System.Drawing.Font("Tahoma", 20, FontStyle.Regular, GraphicsUnit.Point);
 
    Rectangle rectname = new Rectangle(100, 100, xwidth, 100);
   
    StringFormat stringFormat = new StringFormat();
    stringFormat.Alignment = StringAlignment.Center;
    
    flagGraphics.DrawString(user_name, font1, Brushes.Black, rectname, stringFormat) ;
    Rectangle rectnjob = new Rectangle(100, 200, xwidth, 50);

    flagGraphics.DrawString("JOB TITLE", fontjob, Brushes.Black, rectnjob , stringFormat);
    Zen.Barcode.CodeQrBarcodeDraw qrcode = Zen.Barcode.BarcodeDrawFactory.CodeQr;
    var qrcodeimg = qrcode.Draw(barcode_token_key, 80);
    flagGraphics.DrawImage(qrcodeimg, 100, 300, 100, 100);

    e.Graphics.DrawImage(flag, 0, 0, xwidth, xheight);
}

print with:

var doc = new System.Drawing.Printing.PrintDocument();
doc.PrintPage += new System.Drawing.Printing.PrintPageEventHandler(doc_PrintPage);
doc.Print();

If I'm understanding your code, there seems to be some resizing going on that requires interpolation and may be contributing to the fuzziness. In particular, allowing the QR code to keep its generated size, either slightly smaller (91x91) at a scale of 2 or slightly larger (136x136) at a scale of 3, makes the rendering clearer.

I tried to reproduce your issue with a print preview using your code and then compared it to drawing straight into e.Graphics while pretty much leaving the graphics settings alone. This looks like an improvement to me but you be the judge.

private void doc_PrintPage(object sender, PrintPageEventArgs e)
{
    string barcode_token_key = "966819cb72ad75435b87156dc82a9d48";
    SizeF size;
    float x = 100, yCurrent = 130;
    Zen.Barcode.CodeQrBarcodeDraw qrcode = Zen.Barcode.BarcodeDrawFactory.CodeQr;
    var qrcodeimg = qrcode.Draw(barcode_token_key, 0, scale: 3);
    using (var font = new Font("Tahoma", 35, FontStyle.Bold, GraphicsUnit.Point))
    {
        size = e.Graphics.MeasureString("Entrepreneur", font);
        e.Graphics.DrawString(
            s: "Entrepreneur",
            font: font,
            brush: Brushes.Black,
            new RectangleF(
                new PointF(x: x, y: yCurrent),
                new SizeF(width: size.Width, size.Height)),
                format: new StringFormat { Alignment = StringAlignment.Center });
        yCurrent += size.Height + 10;
    }
    using (var font = new Font("Tahoma", 20, FontStyle.Regular, GraphicsUnit.Point))
    {
        e.Graphics.DrawString(
            s: "JOB TITLE",
            font: font,
            brush: Brushes.Black,
            new RectangleF(
                new PointF(x: x, y: yCurrent),
                new SizeF(width: size.Width, size.Height)),
                format: new StringFormat { Alignment = StringAlignment.Center });
        yCurrent += size.Height + 10;
    }
    e.Graphics.DrawImage(
        qrcodeimg,
        x: x,
        y: yCurrent,
        width: qrcodeimg.Width,
        height: qrcodeimg.Height);
}

Alternate

Font 1 size = 10, Font 2 size = 7, height incr = 4