Taking a small image (less pixels) and scaling it up (to an image with more pixels) requires adding more information to the image.
Your options for doing this depend on whether or not this information is available and how you plan to fill in this information (which can depend on where you got the image).
From the internet
If you found the image on the ...
Probably overkill, but DaVinci Resolve - Mac, Win & Nix - is freeware unless you're a pro video editor who needs hardware integretion.
That's literally one of the world's best video edit suites… for free. I honestly have no idea why it's not mentioned in that review, it's right up there with Final Cut Pro & Adobe Premier.
Otherwise, people tend to ...
I personally use ffmpeg using command like:
ffmpeg -i input_file.mp4 -c fixes_input_file.mp4
This help me recover from repeated error with source files in DaVinci Resolve
Also I use (depend of the video) command in this way:
ffmpeg -i input_file.mp4 -c copy fixes_input_file.mp4