There are many use cases where a user would like to set the display type of a custom field based on a required logic.
One of the ways to do so is by using the Set Display Type action in Workflow.
Most of the time, the said action is applicable to custom fields but it should be taken note of that it is not applicable on the following custom fields:
- Inline HTML
The reason behind it is that the said fields were designed to always have an Inline Text display type.
If the user is to create a new custom field of either of the said types, they may notice that on the Display subtab > Display Type field, Inline Text is set, and the field itself is inline, thus, its value cannot be altered.
The same scenario could be observed when trying to edit a custom form. The user will notice that the custom field with any of those types will not have a corresponding display type dropdown field.