These files are NOT official Rockstar releases. They are experimental "Lite" builds or unofficial ports developed by independent creators.
If you wanted GTA V on mobile because you love huge, explorable cities, here are legitimate Android games with similar vibes, all with file sizes close to 2.1GB: Gta V.apk File Size 2.1gb
If you want to play GTA V on your Android or iOS device without risking a virus, you have three legitimate options. None of them involve a 2.1GB APK. These files are NOT official Rockstar releases