Hi Samuel Aderemi, thanks for the question!
If you have any existing Intune Managed Browser policies in place, it can be modified to target the Microsoft Edge browser instead.
To validate your configuration, you may want to create a new policy with the desired settings targeting a test user group prior to deploying it towards all users. You can also ensure the conditions have applied via the steps as documented here.
Regarding Scenario 2 -
The scenario referenced refers to the following: "Contoso has decided that all mobile web browsing access to Microsoft 365 resources must use an approved client app, (like Edge for iOS and Android), protected by an app protection policy prior to receiving access.
If your organization would like to enforce the use of an approved app (like Edge for iOS and Android) prior to accessing company resources, then this may be something you may want to configure.
Hope this helps!