I think summer programs are great for students who want to explore an interest. I don’t think anyone should be forced to do them or worry about falling behind by not doing them.
HappyFace, my D is also a grad of Elliott (double major Intl Affairs and Economics) who was fortunate enough to attend the PA Governors school for international affairs one summer (before it was discontinued.) I suggest your D look into DPE Foreign Service sorority, while I have never been s sorority fan, D made lifelong friends/travel partners there and had some great learning experiences.