To use the theme values just create a theme and provide it to your react-app at the root level:
import { ThemeProvider, createTheme } from "@mui/material";
import { customThemeOptions } from "@hsjobeki/mui-theme";
const customTheme = createTheme(customThemeOptions);
const MyApp = () => {
return (
<ThemeProvider theme={customTheme}>
{/* app content */}
</ThemeProvider>
);
};