- copy
.desktop
file to user directory
cp /usr/share/applications/google-chrome.desktop ~/.local/share/applications/google-chrome.desktop
- modify that file
sed -i 's;/usr/bin/google-chrome-stable;/usr/bin/google-chrome-stable --enable-features=WebUIDarkMode --force-dark-mode;g' ~/.local/share/applications/google-chrome.desktop
edit~/.config/chromium-flags.conf
--enable-features=WebUIDarkMode
--force-dark-mode
Reference: