how to create context for theme with reactjs?

I need to create a context to apply dark or light theme in repositories. There will be no change of themes by button or something like that, I’ll just set the theme and that’s it

for now, I have context like this

import { createContext } from "react";
import { light } from './themes';

export const ThemeContext = createContext(light);

export default ThemeContext;

and my app

import { light, dark } from './themes';


<ThemeContext.Provider value={light}> // or dark, depending on the project
   <App />   
 </ThemeContext.Provider> 
);

that way is not working, how can I apply the theme?