Here's the long story short:

If you just need a one-time unlock and can't afford AnyUnlock, look into the free pyboot or checkra1n methods (iPhone 5s to X only, iOS 12–14). Otherwise, the safe path is either paying for a legitimate license or using Apple's official recovery route.

I understand you're looking for information about "Code d'activation AnyUnlock gratuit" — essentially a free activation code for AnyUnlock, a tool used to remove iOS screen locks (like passcodes or Apple ID).