Proper function in ACS

[#1]

I need to use a proper function to change the case of any field to proper (first letter capital rest small, but acs is not taking this function what can be done?

[#2]

You could use Smart() inside a workflow:
https://experienceleague.adobe.com/docs/campaign-standard/using/managing-processes-and-data/filterin...

Smart

Returns the string with the first letter of each word in capitals

Smart(<string>)

In my case, I created the following content block so I would be able to do the same on single shot deliveries:

<%=context.profile.firstName.toLowerCase().replace(/(^\w{1})|(\s+\w{1})/g, function(e){return e.toUpperCase();})%>

The code shared before, will do what you need with every word in the field, in this case I am targeting the "firstName". This is useful when you have names like "john lucas" -> "John Lucas", as the other functions I found out there only changed the first character ("John lucas").

[#3]

At which place do you need the function?

Inside a workflow, import, E-Mail, ...?