To skip the "Add Details" page in Microsoft Entra External ID after Google sign-in, you need to configure your user flow to automatically provision users without requiring additional input. This can typically be accomplished by setting up the user flow to use the information provided by Google (such as email and name) directly for user creation.
Unfortunately, the specific details on how to bypass the "Add Details" page are not provided in the available context. You may want to check the Microsoft Entra documentation for user flows and see if there are options for customizing the sign-up process to meet your needs.
For further assistance, consider looking into the configuration settings of your user flow or reaching out to Microsoft support for detailed guidance on this specific requirement.