Official music channels (such as Star Music or Sony Music South) occasionally remaster old songs and upload them in 4K. You can use the "Watch Offline" feature on YouTube Premium to download these songs legally in high resolution.
For fans seeking 4K video songs, the visual clarity of Sathyam is a major draw, especially given the film's polished cinematography by R. D. Rajasekhar. Sathyam Tamil Movie 4k Video Songs Download