How to remaster the Old movies to the High Resolution Quality using FFMPEG?
You cannot magically pull out more resolution than the material you have. If it's 1920x1080, the resolution can only get smaller, i.e. 1280x720. There are options like Nvidia's Ai-Upscaling, but it works rather bad when applied to faces, which you'll probably run into. Another method might be to use Red Giant's Upscalers. They use more advanced upscaling methods than After Effects bicubic scaling - however, upscaling 720p to 1080p will not result in a regular fullHD image.