make the field country of birth mandatory in onboarding (person info portlet) for a specific country

[Abbot]

Hello, 

I need to make the field country of birth mandatory in the provide personal data step of Onboarding but only for the country France.

I don't know if it is possible to create a rule to do it as in the information found in this KBA there is no the portlet person info listed: 3052127 - [ONB] How to Enable Fields as Mandatory Field Validation for Employee Central Entities (sa...

Thank you