Request more information during/after the first login flow

Hello everyone! I need help with the following issue as I’m not entirely clear on the approach to be used. Currently, I authenticate users through an external IdP. How can I ensure that after or during the first login flow, the user is required to provide more information about themselves, such as their first name, last name, and also go through a multi-step process to select the group they belong to? Should I redirect the user after authentication to a specific page somehow where they must provide this information if they lack certain attributes?

Many thanks in advance!