There is no such thing as a child opera singer. What she’s doing is mimicry that is taxing her vocal folds well beyond what a child’s vocal folds are meant to withstand. People who study singing opera usually don’t get to stuff like Verdi and Puccini until grad school.
This is the truth. My daughter is 17 and after 2 years of classical vocal training is singing art song repertoire. She had a sample lesson at a well known music conservatory and was told they start all freshmen ( 18 and 19 year olds) with beginning art songs. Opera is a very long haul career, and the heavy repertoire often doesn’t start until graduate school. Female Opera singers are beginning careers in their early thirties and often male voices aren’t fully developed until they are in their 40’s.