[keycloak-user] SSO amongst two realms

Hi, I want to know whether it is possible to have SSO amongst two realms. Ie User 1 logins to an app1 that auths against realm1, then user 1 tries to use app2 which auths against realm2 which should work fine as user 1 logged into realm1 before and it should SSO into app2 fine. If this is possible then what would be the setup like? Kind Regards, Sarp