Think about a picture when you upscale it. Except the most recent AI-based which have real reconstruction of picture, all other upscaling methods use various recipes to allow your picture to look bigger without having visible pixels. Upsampling works a bit like that, with sliders to optimise the result (we even use common vocabulary sometimes such as anti-aliasing). It will not revert the alterations compression created (this isn’t a remastering function). I don’t know if it’s very useful on heavily compressed files, people usually use that with lossless content (like FLAC). But sometimes, a higher sound resolution can help an audio equipment to work better (despite the sent audio signal not being in a better quality).