I believe the issue to be when designing a schema for an empty feature class. In a FGDB, in Catalog, I'm able to add a new text field with default, apply and close, edit the field to be shorter or longer as many times as I want. In Pro 2.3.2, I can only increase text field length. When I decrease, upon loss of mouse focus, it reverts to the original length. Bear in mind, this is on an empty feature class.
Changing text field lengths is a pretty common workflow for us, we have a plethora of data standards and the mandatory field lengths of our many text fields is not always memorable (eg 50 or 255, often something like 10 or 4 instead), therefore "forgotten" 'till we review work, hence needing to increase or decrease.
As such, this seems like a bug (can do it in Arc, not Pro). If you agree, Kerry Shakarjian or myself can log a case.