Sadly, seats cannot be scaled directly.
However to reach a similar goal, we can make other objects smaller or bigger compared to the seats or adjust the spacing around them.
Enlarge or Shrink the Section
If your section is disproportionate in relation to its contents, you can scale it up or down.
Follow these steps:
Open your chart;
Select the section you want to rescale;
Locate the Transform property located at the right-side panel.
Move the handle to the right to make it bigger compared to the seats (so the seats will look smaller in comparison), or to the left to make the section smaller (so the seats will look bigger in comparison).
Increase Spacing Between Seats
Shrink or enlarge the space between seats to not only modify the spacing itself, but to make seats look bigger or smaller.
Follow these steps:
Open your chart;
Select the rows you'd like to adjust;
Locate the Seat spacing and Row spacing properties (row spacing is only available when selecting multiple rows);
Increase the values of these properties to make seats seem smaller, or reduce the values to make them look bigger.