How do I sync the Visual Studio Code (vscode) theme to use my OS light/dark color scheme?

This was released in 1.42:

Auto switch Theme based on OS color scheme

Windows and macOS now support light and dark color schemes. There is a new setting, window.autoDetectColorScheme, that instructs VS Code to listen to changes to the OS's color scheme and switch to a matching theme accordingly.

To customize the themes that are used when a color scheme changes, you can set the preferred light and dark theme with the settings:

• workbench.preferredLightColorTheme
• workbench.preferredDarkColorTheme

Go to settings and search for theme -> Auto Detect Color Scheme