So regarding the car sitting higher on 19" rims, it’s likely not as high as you think because of just the rim size difference.
For reference, the calculation to find out wheel height is: tire width (in mm) times sidewall height percentage times two (because the overall wheel diameter has two opposing sidewalls and rim is measured in diameter, not radius) divided by 25.4 (to convert mm to inches) plus rim size.
However, total wheel height should be divided by two as the center of the wheel to the ground is what is changing from wheel size between models. From the wheel mounting point and above ends up being suspension/chassis.
Google says 2020 Q3 has a tire size of: P235/50R19
So the math works out to: 235 x 0.50 x 2 / 25.4 +19 = 28.842 inches
Divide that by two to get 14.421 inches
Similarly, a 2020 A3 has a tire size of: P225/40R18
So the math works out to: 225 x 0.40 x 2 / 25.4 + 18 = 25.087 inches
Divide that by two to get 12.544
Thus, the height of a Q3 compared to A3 is less than 2" difference due to wheel and tire size differences.
Hmm. I just looked up the height difference. A3 is 56" high while Q3 is 63" (and Q5 is 65").
So most of the difference in height is between longer suspension and taller chassis/cabin.