Rich text editing has been an ask of Dynamics 365 for a long time. Now, such controls have appeared in the Unified Interface but only in a limited way.
In my moderately brief review, I see the position as this:
- Rich text controls are available in the Unified Interface for Dynamics 365 Online version 9.0
- They are only available for the Content field in Knowledge Articles and the Description field in Emails
As far as I can see it is not possible to have the interface show rich text controls for any other field.