https://stackoverflow.com/a/45671704/10130690

• Open the Command Palette (CtrlShiftP | macOS: ⇧⌘P)
• Preferences: Configure language specific settings… (command id: workbench.action.configureLanguageBasedSettings)
• Select programming language (for example TypeScript)
• Add this code:

    "[typescript]": {
        "editor.tabSize": 2
    }