To start with the pronunciation, it’s “eh PIT o me.” I once heard a famous wine expert describe a particular wine as the “EP i tome” of its kind. Just another day when I yelled at the radio and did an impressive eye roll.
As to its meaning, if you read that “the Taj Mahal is the epitome of a gorgeous building,” it doesn’t mean it is the most beautiful building in the world. How could anyone know that objectively? You are stating that the Taj Mahal is representative of, typical of, an architectural masterpiece.