Virtually any graphics program should let you resize an image. Microsoft Paint comes standard on computers with Windows. Go to Image > Stretch/Skew and then "stretch" the image to 50% or so in both height and width.

And I've never tried this one, but including a link to an online image resizer that might get the job done just as well.

Here's a free program

I use this one a lot and love it.  Once you install it, open up an image, then go to Image - Scale Image - then you can input what size you want in inches, cm, or pixels.

This tool also lets you blur your face or crop the image or whatever you want really.  There's a lot of features if you take some time and learn how to use it.  And it's 100% free and legal.