Hi @sanio, I have a template in which I use the date format calculation to produce a timestamp that I can use as an ID.
When the date is auto-populated, it still shows up in the live form as something like "Thursday, July 29, 2021," but when the observation is submitted, another field records the full and reformatted dateTime as "20210729044923." You can see this in my screenshot under the read-only "Feature Timestamp" field.
Apologies, I'm not exactly sure how to adjust the appearance of the date in the form view unless you do something like I did by printing a read only field just below with the dateTime reformatted as you want it to appear.
Kindest Regards,
t