Thanks Robert,
I'm not getting the same behaviour. I'm on ArcPro 2.7 and using the tool within modelbuilder. But as you can see the "Field Type" setting is not appearing.
The yellow warning next to field name is to inform me that the field doesn't exist and will be created.
However, I just tried it with the original input (not intermediate data) and that dropdown does appear. So it would seem for intermediate data the "add field" tool would need to be run first.