You still need the full 100 GB install. The game does not become smaller for low-end PCs.
The original GTA 5 requires roughly of disk space. If you need a smaller download due to slow internet, these are the only legitimate "highly compressed" options (known as "repacks"): Minimum size: Around 30GB to 45GB . gta 5 highly compressed 500mb for pc link
Protect yourself with these red flags:
requires approximately of storage space depending on updates and mods. Why "500MB GTA 5" is a Myth You still need the full 100 GB install
Technical experts and the gaming community agree that shrinking a 100GB game to 500MB is virtually impossible without losing almost all the game's data. gta 5 highly compressed 500mb for pc link