You could draw the path onto a bitmap and zoom into that. But the pixels will get interpolated, even with Graphics.SmoothingMode set to None.
So if you really want to see pixels, you will have to repeatedly FillRectangle. One square for each pixel of the mentioned bitmap.
Oh, and ... Why?
Bitmap ZoomPixelish(Image original, int scaleFactor)
bitmap zoomedImage = new Bitmap(original.Width * scaleFactor, original.Height * scaleFactor);
Graphics g = Graphics.FromImage(zoomedImage);
for(int y = 0; y < original.Height; y++)
for(int x = 0; x < original.Widht; x++)
x * scaleFactor,
y * scaleFactor,
That's not tested. But you should get the intention. Bugfixing and optimization are up to you (a black-and-white image doesn't need a new SolidBrush for every pixel; LockBits instead of GetPixel)