Let's be brutally honest. If you restrict the definition to "actually giving you server-sided permissions you didn't pay for," the answer is
To run any script, you need a Roblox exploit/executor. Many fake YouTube descriptions will say: “Download this custom executor to run the gamepass script.” That .exe file is often a RAT (Remote Access Trojan), keylogger, or cryptocurrency miner. - FE - Universal FREE Gamepass Script - ROBLOX ...
Assuming you find a working script (very rare), what is it actually doing? Most "FE Universal Free Gamepass Scripts" rely on one of three exploit methods: Let's be brutally honest