Android 9.0 pie user can enable dark mode on Google chrome , however it is still on experimental stage. But in 99% cases, works fine on my k20 pro.

1. enter chrome://flags in the browser's address bar
2. Tap the 'Search flags' box and enter the work dark.

You'll find two options here: 'Android web contents dark mode' and 'Android Chrome UI dark mode'.

3. Tap the drop-down menu under each of these options and change the setting to 'Activated', then restart Chrome.

4. Now Chrome > settings > themes >Dark

5. Restart the chrome, CONGRATULATIONS dark mode enabled