The following block in "settings.json" colorizes (), {}, [] :

{
    "workbench.colorCustomizations": {
        "[One Dark Pro]": {  // the colorscheme I am using
            "editorBracketHighlight.foreground1": "#bdb2ff",
            "editorBracketHighlight.foreground2": "#80c4ff",
            "editorBracketHighlight.foreground3": "#acdcdd",
            "editorBracketHighlight.foreground4": "#baff8f",
            "editorBracketHighlight.foreground5": "#fdefb6",
            "editorBracketHighlight.foreground6": "#ff8dad",
        }
    }
}