Auto-Dark is an auto-changer between 2 themes, dark/light, respecting the
overall settings of MacOS, Linux and Windows.
To enable it, install the package and add it to your load path:

    (require 'auto-dark)
    (auto-dark-mode t)

To customize the themes used by light/dark mode:

    M-x customize-group auto-dark

If you're using Doom Emacs or Spacemacs, follow the installation tips
on https://github.com/LionyxML/auto-dark-emacs.