If you mean that KiCad needs dark mode, this can be done using a combination of GTK (or QT?) color themes, which are associated with your system configuration, not KiCad, and color themes for the editing tools, which can be changed in the preferences menu. I found some reasonable options here [1], but if you're picky (like I am), you can write (or generate) your own. In the current version of KiCad, you can choose between themes (files in the appropriate directory) with a drop-down menu in the KiCad preferences, rather than editing the default configuration.
