Can the FBI track me if I use a VPN?

Can the FBI really track me even if I'm using a VPN? I've heard that VPNs are supposed to provide a secure, encrypted connection, so I thought it would keep my online activities private. But now I'm not so sure. Is it possible for the FBI or other law enforcement agencies to bypass the encryption and monitor my activity? Or are there certain circumstances where they can request access to VPN logs or data? I'd like to know if there's any way to stay truly anonymous online, even when using a VPN.