How to read custom params set in logout

I am using @auth0/auth0-react in my react app, I also configured a custom login in Auth0 that I custom an html page for the login page.
Now In my react app, I want some cases to logout the user and send custom data to the “custom login” page.
As per LogoutOptions | @auth0/auth0-react
I am able send custom params [key: string]: any; in logout function.
I tried the following code:

      logoutParams: {
        returnTo: `my_url`,
        myCustomParam: true, // try #1
        appState: {
          myCustomParam: true, // try #2

Now in my custom login I am using ‘auth0-js’, how can I read the myCustomParam here?