Hi Emam,
There is no built-in date-time type for properties. If you want that, you have to either make your own with concepts and then use it as a child, or you could use the prebuilt types from KernelF. But again, it's only possible as type, not as property.
If you are ok with very basic regular expression checking, you could also consider making a constrained datatype and specify a regular expression in it that will make the property at least comply to a certain format like 20200125.
Greetings,
Eugen
Sent from a magical device living in my pocket. Please excuse typos and brevity.