Audacity will indeed normalise amongst many other things. I normally digitise well below 0dB then normalise the result. There is probably a facility to search for the peak level but I've never used it, just being a casual user.
There are many examples where professional mastering engineers (or rather, their producer bosses) have deliberately clipped peaks to make the recording sound punchier on cheap equipment, a lazy and shortsighted attitude. See
https://en.wikipedia.org/wiki/Loudness_war