If you're a Linux user and want to resize images in the terminal, you'll need to install a software suite like ImageMagick ... and GIMP. Some are free or have free basic versions, and others ...

Light Image Resizer is a user-friendly software designed to help users resize, convert, and optimize images quickly and easily. It supports a wide range of formats, including JPEG, PNG ...

Keep in mind you can only upscale a few images for free before you have to pay up or wait. That's true of most AI-based upscalers. As you can see, there are plenty of options for resizing an image ...