Ask HN: How do I setup SSO and SLO on my two WP websites with separate databases

I am building a website and want to connect it with its subdomains so that when one user login to main domain he is automatically logged in to all subdomains and when some user logsout it happens in all websites.

I tried using Auth0 but after all the efforts I put in it, it still doesn't do what I wants like I tried creating acount on main domain so it should have created on subdomain but no it is not then I tried asking gpt and it is as dumb as a donkey so I need professional advices.