How do I embed a ServiceNow portal page on an external site in an iframe?

[Yuri____]

I want to embed a ServiceNow portal page into a SharePoint site using an iframe.
SharePoint and ServiceNow use AAD to set up SSO and SSO works on its own.

I want to achieve the following transitions within the SharePoint frame:

1. ServiceNow page

2. Microsoft Authentication page

3. ActiveDirectory authentication page

4. Microsoft Authentication page

5. ServiceNow page

However, because the domains are different in SharePoint, ServiceNow, and Microsoft Authentication page,
When opening the “2.Microsoft Authentication page”, the cross domain policy causes an error and the screen transition does not take place.

[Mark Manders]

If you are getting stuck on opening a Microsoft page from a Microsoft application (SharePoint), it may be helpful to ask this on the Microsoft community.