I am looking for a program that can Scale images by a factor of around a 1.5 -2x scale factor. I haven't seen any programs that aren't behind a paywall. Any help would be appreciated, thank you.
I like to use GIMP image editor. GIMP is a free, cross-platform image editor available for GNU/Linux, OS X, Windows and more operating systems. It has a toolbox full of useful tools for manipulating an image after you have rescaled it.
Also useful with GIMP is another app named Simple Screen Ruler. This app displays a ruler on the screen. You can measure objects with a ruler that is shown on the screen. Download this app from Microsoft Store for Windows 8.1 and Windows 10.
I'm surprized no one mentioned ImageMagick, it's the reference in command-line FOSS softwares for image edition, specially batch edition. It's cross-platform and present by default in many Linux distributions. Definitively a must.
There is a free and open source command line tool GraphicsMagick
It allows to manipulate images from command line, including resizing.
Check out a-sharper-scaling, I've been using it with good results, also it's free-ware.