Yes, that right. This is an example of deductive reasoning.
Rule: All persons under the age of 18 have limited legal capacity
Facts: Paul is 17 years old.
Conclusion: Therefore Paul has limited legal capacity.
Deductive logic is a process of reasoning from generalised statements (premises) towards a specific conclusion.
In the example, the first statement is a general rule. The second statement represents the facts of a specific case. The third statement is the conclusion reached by applying the rue to the facts.