The very first scene of the movie is of the ice harvesters singing "Frozen Heart" while they cut the ice to sell to the people during summer. The lyrics were something I initially looked past but analyzing them further, it very clearly references Elsa and her power:
The first line "Born of cold and winter air" can clearly reference Elsa's power that she was born with. The song continues to talk about cutting through the heart and recognizing that though it is feared, it is still something to see beauty in. Lastly, defining ice, or Elsa, as "beautiful, powerful, and dangerous" gives her recognition as a strong and powerful woman but also a negative connotation as the whole song is talking about breaking the "frozen heart". This scene initially foreshadows the themes of the movie and the problems Elsa will come to face throughout the film but again, also recognizes that there is beauty to her power and really sets the film up.
One of the great moments in the beginning of the movie is Elsa's coronation. Three years after dealing with the loss of her parents, Elsa has the staff open up the doors to the castle and allow the people to enter the castle for the day. Very briefly, as there is a panned scene of Arendelle, a woman is talking to her son and is very excited because Elsa has finally come of age to accept the role as Queen of Arendelle. During her coronation, the only doubtful person in the room seems to be Elsa herself. All that attend the coronation very willingly accept her as ruler of Arendelle even though she is a woman. In many of Disney's past movies involving a princess, the roles they have played were minuscule in regards to actually ruling a kingdom. Creating a female character with that much power as well as fully accepting her in the eyes of the country was a big step for Disney.
This scene of the movie, I believe, is Elsa's defining moment as a strong and determined female leading character. In the middle of her big musical number, she gains confidence in herself and it empowers her to find beauty in her ability. Something pointed out to me was that often, when a problem arose for a Disney princess, they would become overwhelmed by it, run away, and cry. Minutes before this scene, when Elsa's power becomes exposed, though she does run away, I believe she does it for fear of people fearing her. In her song "Let it Go", below, at 2:08, Elsa exclaims "You'll never see me cry." This line itself speaks for how strong her character is and defines her as an independent woman who has accepted every aspect of herself and continues to not let it bother her.
Another defining moment for Elsa is during a reprise of the song "For the First Time in Forever". As Anna pleads her to come back because she finally understands what Elsa has been going through, Elsa explains that her decision to be on her own, though it has resulted in her being by herself, has also allowed her to fully be herself. Many times in movies, the characters that willingly choose to be alone tend to be the villains of the movie. Elsa's decision to be independent for her and at the same time not be evil shows a new side to Disney in that, plainly stated, you don't have to be evil to be independent.
Pictured above (1 & 3) are two depictions of Snow Queens. The first one, also known as the White Witch, is a completely evil character who uses her powers and lures people in only to fulfill her bad intentions. The third picture is of the fable of the Snow Queen, an evil woman who, like the White Witch, lured children in through false acts of kindness only to kill them. Though these are just two instances, every compilation of the character of the Snow Queen until Frozen has been evil and manipulative. Shown in the center is Elsa as the Snow Queen, originally intended by Disney to be an evil character. Disney, however, did not go with its original plan and recreated Elsa still as a strong independent woman but also as loving and charismatic. She has been the first depiction of the Snow Queen that has not been evil in nature, again reaffirming that you can be both a woman and powerful but you don't have to be evil to be that way.