About music supplements

What kind of (top) universities would accept supplements as part of their admission process? For instance, I’m aware that MIT accepts supplements of all kinds.

Another question - I want to major in Materials Science and Engineering, while I enjoy music a lot (both singing and composing). What kind of music pieces would a high-quality supplement?
For singing, my choral teacher suggested “Thou Art Gone Up on High” from the Messiah, but I don’t really know how other people find this piece to be (at least it’s easy for me, so I’m doubting its “impressiveness.” For composition, would it be better for me to rearrange some pieces from Mozart’s Requiem or would it be better to compose something completely of my own? (I just find it hard to actually develop a music theme and sustain it.)
I know this is soooooo “wrong” to just try to impress the admission officers, but I do want to show my singing and composition skills so that they will know me better as an individual. Any advice PLS?

Try posting in the music majors forum. Even though you’re not applying as a music major, people would have tips for you there. Both my older sons submitted music supplements. My oldest, graduating from MIT this year, did violin, and my middle son, a rising freshman at U Penn, did cello. Each submitted two contrasting styles for their two pieces. Sorry-don’t know anything about voice.

@sbjdorlo thank you!