You don't actually need a third-party plugin to upscale footage effectively. Adobe included a "secret weapon" in After Effects specifically designed to compete with Instant 4K. How to use it: Import your 720p or 1080p footage. Go to . Click Fit to Comp Width (ensure your comp is 4K).
There is no widely known, reputable plugin called "Instant 4K." This phrase is almost certainly used by: instant 4k plugin after effects free
If you specifically want third-party tools, some creators use free AI-based upscalers like You don't actually need a third-party plugin to