My D was attends a T20 engineering program and except for being a member of her high school robotics team, she had pretty much no STEM activities. And even on robotics her role on the team was not very engineering focused (she didn’t do design or anything) - she had athletic activity that took up too much time to take on that large and important of a role. She worked as a math tutor and took lots of math and science classes, but that’s about it.
I think instead she presented herself as an interesting and well rounded student. Maybe that was a turn off for some schools but it worked for others!