The difference is that she's and similar shortened forms are used in colloquial speech, but not in certain cases. In your example, she is being emphasised.
When to use "she's" (short form) and and "she is" (full form)? What is ...
In short, "she/they" is the most common way for a person to indicate that they go by "she/her" or "they/them" pronouns, likely with a preference for the former. It is not incorrect. Note: While "she/they" is commonly used by feminine-leaning non-binary people, a great deal of women (both cis and trans) also go by it.
Is it correct to say your pronouns are "she/they" or should it be "she ...
Taken from the Free Online Dictionary: Usage Note: Using she as a generic or gender-neutral singular pronoun is more common than might be expected, given the continuing debate regarding the parallel use of he. In a 1989 article from the Los Angeles Times, for instance, writer Dan Sullivan notes, "What's wrong with reinventing the wheel?
word usage - Reason for the current trend to use «she» as the gender ...
She was in on the drama when the conman showed up at the stage door. If you are an actor in something, it's in: She was in Cat on a Hot Tin Roof. She was in the movie Cat On a Hot Tin Roof. She was in several West End plays. VERSUS" to be on TV to be on the radio to be on tv or the radio just means that a person has been recorded in that medium.
She was "in" or "on" the show? - English Language & Usage Stack Exchange