When adding a contact via the lookup field to an Account or Opportunity, you have the option to add a new contact if the person you want is not yet listed in Dynamics 365.
However on a Case you cannot do this, which is frustrating for the Service team as they need to navigate away from the case to add in the contact, then come back.
Specifically, this is what we see for an opporunity:
When it comes to a Case, I see the following:
Is there a setting to allow this?
Note: I can see that in the old web interface you bring up "more records" and can add a new contact.