Hi @y-watanabe,
Welcome to the Auth0 Community and sorry for the late reply.
You can use a post-login action that checks for sign-up by querying if the event.stats.logins_count is equal to 1, then use something that looks similar to this:
const returnTo = event.client.client_id; api.redirect.sendUserTo(‘https://{{auth0_domain}}/v2/logout?client_id=${returnTo}’);
In this case, the Action will redirect to the first Allowed Logout URL configured in the Application you use to perform the login flow. This is mentioned in the following Knowledge Article as well.
Additionally you can also check out the Redirect users with state option.
I hope this helps.
Thanks,
Remus