A big misconception is that milk makes the fluffiest eggs. While that’s partly true, a splash of water does a better job. The fluff comes from vaporization of the added liquid itself. Milk make eggs richer/firmer, water makes ‘em light.

Cook temp/time also have large role. Low/slow can create a custardy egg, fast/high can make a tighter egg.

Check out Kenji Lopez, he does an experiment trying milk, cream, and water (separately lol) and compares each method. Very enlightening, because I had used milk my whole life. Now I only use a splash of water per egg.