Each era has a "look" which women of the time aspire to. This is the "look" which nineteen-twenties young women wanted to achieve.
Whether they succeeded or not is history but it can help in dating portraits if we recognise their ambition.

Women have the faces nature provides, it is only make-up, hairstyle and clothing which can change. Her face peeking from under her cloche hat this woman has the look of the twenties.
She has button mouth with a cupid's bow top lip. Large full lips on a woman would be considered "coarse".
The 1920s woman did not want "coarse features".
The side curls of an orchid bob hairstyle lie on each cheek.