Depends what you want. Every player can upscale a video, you just have to resize the player window, but they use fast and poor quality algorithm by default. Some players will let you choose better ones and some will have stuff like shaders you can apply to the video to do some processing.
But if you use mpchc or any supported directshow player, you can select madvr as the renderer and that has a really wide choice of real time upscaling and downscaling algorithms as well as many more processing options to make things look better. You just have to find the right balance for what your pc can handle with it.
I prefer madvr since it has many options and is pretty easy to set up, just install it, select it in mpchc and adjust the settings however you want. There's many guides out there about it.
The NGU stuff is based on the same nnedi3 thing porni mentioned and he was also the first to mention madvr. It can be a bit demanding though, but there's also other good options(and more versatile since it can only exactly double) if your GPU can't handle it.