Make a field mandatory in Enterprise Portal

Hello,

I know I can make a field mandatory at table level and it shows in the client with a red line but in the portal the typical red star does not show.

Which is the step by step procedure to allow this?

I have seen this

https://community.dynamics.com/ax/f/33/t/178065

But I don't know how to identify that I should modify and where (AOT directly, Visual Studio).

Thanks