Sorry, but new to Jailbreaking. Will jailbreaking my old iPhone 3gs with 6.1.6, allow me to use apps built for iOS 11 ? Also will jailbreaking allow me to unlock the phone, currently tied to 3mobile?
Operating system requirements for apps have no relationship to jailbreaking. iOS 11 apps are all 64-bit, and the 3GS's processor cannot run 64-bit applications at all.