You do not need extracurriculars related to your possible majors when applying to an Arts & Sciences school like Trinity. In fact you don’t even declare a major in Trinity until your sophomore year, and even then you can change it. Instead, the whole point of schools like Trinity is to explore options before narrowing in:
https://admissions.duke.edu/trinity/
TRINITY COLLEGE
AN EDUCATION DESIGNED FOR EXPLORATION
With over 50 million ways to navigate the curriculum, Trinity College of Arts & Sciences fosters student creativity and curiosity in the classroom. Trinity students embrace our flexible liberal arts curriculum by blurring, crossing, and mixing traditional academic boundaries—all with the support of faculty, advisors, and their peers. . . . 80% of Duke undergraduates are enrolled in the Trinity College of Arts & Sciences. Trinity offers 48 majors, 50 minors, 23 certificates and an option for students to design their own major. Students can combine up to three academic pathways and they do not have to be related. With a flexible liberal arts curriculum, students explore diverse disciplines and create new ways of combining them together.
OK, so Trinity isn’t really looking for kids who think they decided what they want to do for a major and occupation when they were 14 or 15, and since then have been devoting themselves to just that one area in both classes and ECs. They are looking for kids who will enthusiastically explore the many different things that Trinity offers academically, possibly in unexpected directions and combinations, while being active participants in campus life in other ways too.
And you can do all that while being pre-med. But like many people, you may also start pre-med but discover in college that you have interests and aptitudes that lead you in a different direction. One of the great things about a school like Trinity is no matter how your path may evolve, it will be well-resourced.
Of course if you want to be an engineer, you should prefer Pratt. But if that idea of an exploratory, flexible, liberal arts and sciences experience appeals to you, then you should prefer Trinity.
And on the third hand, if you feel sure about pre-med and just want the best chance of med school admissions while minimizing pre-med-school costs–Duke may not actually be the best choice at all.