This is a quite classic misconception.
You could in the digital case use a limiter, but it will sound unnatural.
The piano raises its total volume when you play more and more keys in almost the same way playing the same keys as samples in a virtual instrument does (there are of course more advanced physical processes going on, but overall, the volume will act the same).
FWIW, the volume does not get 10 times as loud when playing 10 different piano samples at once instead of just one
More like, maybe around 9dB or something, which is about 2.8 times as loud, linearly speaking. You can however get peaks that are at values 10 times as high as when playing just one sample, but that applies in both the "real" and the virtual domain.