Janet S. answered 11/03/24
Veteran Lang Prof Offers Spanish, French and English Lessons
I understand your confusion, because the verb form for the second person formal pronoun "usted" is identical to the third person singular form (él/ ella). However, the fact that the verb form is the same does not mean you are not addressing the person directly in saying "¿Es Ud. panameño?". The pronoun "usted" may or may not be expressed explicitly, but it is understood.
Typically the subject pronoun "usted" is expressed more frequently than the other pronouns, precisely because the verb form is ambiguous. If you were to say "¿Es panameño?" rather than "¿Es usted panameño?" it might cause confusion, unless it were very clear in the context that you were speaking directly to the person in a formal register.