Over the yesteryears, SuperUser was the most popular root manager. It is still awesome but limited in functionality.
Nowadays, Magisk is getting more popular. Thanks to topjohnwu@xda who made this awesome systemless root application with great features. Being systemless, you can hide root from an app using Magisk Hide feature.
To root LG K20 Plus with Magisk follow the below step by step tutorial
How to Root LG K20 Plus MetroPCS & T Mobile with Magisk
Before rooting you have to –
Now that you’ve installed TWRP, follow the steps below to get your device rooted –
Step 3: Download and transfer Magisk.zip file to Phone’s Internal Storage or SD Card