Current Official LineageOS build don't have option to enable native root for apps. For getting root access for apps, you need to flash SuperSU or LineageSU trough TWRP Recovery or other custom recoveries compatible with nougat.
You can follow these simple steps to enable SuperSU and get root access on Lineage OS roms properly. You don’t need to flash supersu.zip on CM 14.1. This is the latest CM 14.1 rom based on latest android os. You can root android Lineage OS easily without PC by enabling it native root priviliges first.
Lineage OS rom comes with native (inbuilt) root access setting in developer option. You just have to enable it for adb and apps. This way is very simple to do.
For enabling root access or in other words, rooting Lineage OS, please do follow step by step below
Note: Lineageos rom is not yet release but as we know that lineageos is also based on Cyanognemod ROMs, so the root method of Lineage os is also same as rooting Cyanogenmod rom's way.
How to Enable Root Access In Lineage OS
1. Firstly, go to Settings on your Lineage OS rom.
2.Now open About phone menu in the last.
3.Then tap on Build Number 5-6 time to enable developer option.
4.After developer option enabled, Go back to Settings and open Developers options menu.
5. Now turn on the Developer option by sliding the switch to ON.
6. Then scroll down and choose Root access option.
7. From the menu select enable Root for apps and Adb.
8.Done! You successfully enable Root access on Lineage OS
Now you can download SuperSU app in playstore and installing it into Limeage OS. Do the instructions to replace native Lineage OS root management with SuperSU. You can choose normal options.
That's it! SuperSU now installed, and root access can managed easily trough SuperSU app.