You might find it necessary to crop images a bit, but you could get by if you can get to within 10-15 feet of the stage. As others noted, when you get that close, the angle can be a issue, you are looking up at the subject.
If you have a longer focal length lens, take it along.
When I can pick a seat, I prefer my 135mmL. However, a zoom can save you from embarrassment.
I arrived at my son's graduation 2 hours early, picked a seat 8 rows back, and thought I was set. However, he was a bit taller than average, so the top of the image of his mother moving the tassle on the Motarboard was cut off.
He was home schooled, but under supervision of the local school board, which means he received a full diploma. About 30% of the students get their community college 2 year degree at the same time. Parents give out the diploma and excessive cheering is encouraged
A little photoshop work to modify the sign on the venue makes for a nice senior book cover.
I was setup perfectly for the student performing without having to crop
But ... at 6'8", he tends to rise out of the frame. (I did get lots of good images) That's the danger of using a prime, I did not know exactly where they would be standing.