Upscaling Featured Image

Hello. Our old theme uses images that were uploaded at a slightly smaller resolution than what we will be doing with our blog posts for this Enfold theme. We do not want to go back and re-upload higher resolution versions of hundreds of our older images in order for them to meet the slightly wider and taller dimensions that we have specified in enfold.

I know some themes will automatically upscale the image to the correct size (e.g., Divi theme), but I noticed that the Enfold theme keeps the smaller image at the same size that it was originally uploaded at (regardless if I have specified a larger size in Enfold). Is there something that needs to be tweeked in the theme or the settings to allow the images to upscale a little bit so that they will match the size that I am setting in Enfold?