دَخَلَ رَجُلٌ، فَسَأَلَ الرَّجُلُ عَنِ الْمُعَلِّمِ.
A man entered, and the man asked about the teacher.
The first rajul introduces a participant; the second definite expression refers back to the same participant by previous mention (ʿahd dhikrī). Reading the article here as automatically expressing magnificence would ignore its referential job.
An indefinite noun may introduce someone, identify a kind, or leave an identity unknown. Its evaluative effects—magnification or belittlement—require specific context rather than automatic assignment.