Dark mode sometime feels very essential but you don't wanna keep a separate app for that. Here's the solution but for now, it's only for root users (sorry non-rooted androiders, but there are tons of ways to get that).
You need :
1. Xposed Installer
What's Xposed?? Know here-https://www.guidingtech.com/26762/xpo...
How to install it-https://android.gadgethacks.com/how-t...
2. Settings Editor Pro:http://server02.dropapk.com:182/d/axc...
3. Material icons [Updated]:https://github.com/google/material-de...
Have fun!!