Move it up/down left/right and its position on the screen/ stretching....is there such a thing
Many of the Extron RGB processors have controls for horizontal and vertical centering. I have the
Extron RGB 201 Rxi and it works very well for this. It has a VGA input and BNC outputs.
As for adjusting the size, I can't imagine there will be a solution that doesn't mangle your video signal and introduce all sorts of scaling artifacts. Better to adjust the the H and V directly size on your display if you care about image quality. Less convenient but a better result.