how to jailbreak a device by apple ruining on iso 11 here is the procedure and files that you need to install electra and cydia to you device very easy.
Tutorial
page to access from safari
next.tweekboxapp.com
search in apps> tweekbox app> Electra install it
allow permission from settings>general>profile then trust it
run Electra click jailbreak device reboot and there you have it if no cydia after jail break follow
https://free4alldevices.blogspot.com/2018/04/cydia-fix-ios11.html
Enjoy it run on my iPhone 5s ios 11.2.1