I need this feature too. So do other users, and many requested this feature back in 2014. Steinberg, are you listening? Here’s the thread:
At present, Shift-H zooms in vertically in the waveform Editor, which is good. But in the Project Zone, it expands the whole track vertically instead. That does not allow enough expansion to see small-amplitude waves clearly, so it’s not sufficient.
In the Project Zone, the Shift-H keyboard shortcut should do what the little vertical slider does: expand the actual waveform, not the track. That would be consistent with its functionality in the waveform Editor.