Actually, from a very young age, the Su family members all begin to learn these things. It is important to note that one of the most special family rules of the Su family is that the children do not have the right to make decisions on their own before they get married. Many arrangements are to be followed according to the family's wishes, otherwise, Su Yanyi also would not have entered into a marriage contract with Qin Jiran just for the sake of autonomy.
However, fortunately, the children of the Su family are all very sensible and mature early. They not only do not reject these arrangements, but also study them very seriously, just like Su Yanmo and Su Yanyi when they were young. They not only studied these courses diligently but also took the initiative to learn other courses, otherwise Su Yanmo would not be proficient in multiple languages, and Su Yanyi would not be so familiar with various combat techniques.