We are fortunate that YouTube abounds with examples of Lucia Popp's singing. I coujld post gazillions of videos, but these three will suffice.
As Pamina in Die Zauberflöte, Vienna, 1983. Watch all the way to the end to see her utter resignation at what she thinks if Tamino's betrayal. My
From Le nozze di Figaro, Paris, 1980, cond. Georg Solti. A beloved Susanna, she also sang the Countess later in her career.
Mr. J. Strauss's Frühlingsstimmenwaltzer, in a 1965 movie. No further information is given.