I copied this from a post
@lime73 posted, I copied it to my phone, works well. Hope it helps.
How to enable dark mode for Google Chrome
By Cat Ellis August 13, 2019
Enable dark mode for Chrome on Android
1. Dark mode is still an experimental feature in Chrome for Android, so bear in mind that some design elements might look a little strange. To activate it, 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'. If you activate the first option, Chrome will detect if a site's developers have created a dark version and select it automatically. If there's no dark version available, the browser will invert the site's colors. Activating the second option means that the browser interface itself will turn dark.
3. Tap the drop-down menu under each of these options and change the setting to 'Activated', then restart Chrome.
4. Now open the settings menu, tap 'Themes' and select 'Dark'. If you can't see the Themes option, restart Chrome again and it should appear.
Enable dark mode for Chrome on iOS
Google hasn't released a dark mode for Chrome on iOS, but it's a work in progressand may become available with the browser's next major update.