A Doll's House is one of the first plays that fell under the genre of Realistic Drama. Realistic drama became popular in the middle of the 19th century. Prior to this time, the usual genres for plays were either heroic dramas or Romantic dramas, and the French drama also known as the "well-made" drama. In both, people were idealized, the language was exaggerated, the themes were historical or mythological, and the overall style of acting was very affective.
Realistic dramas, contrastingly, for the first time presented a typical scene of a typical moment in real life, spoken naturally, and getting away from overpowering language, intonation, or gestures.
Since the character of Nora is already dramatic and exaggerated, she would accentuate the realistic nature of the acting with her character's personality traits. Other than that, realistic drama is typical, expected, and as natural as can be.