What does automatic pitch trim is available mean, when bank angle is below 33°?
In the context of the A320 as you are describing, pitch trim does not mean trimming with the horizontal stabilizer. Instead, it means that up to 33 deg bank angle, no aft stick pressure is needed to maintain horizontal flight, or more precisely, the load factor (for example, at 33 deg bank, the load factor is approximately 1.15g).

Up to 33 deg bank, the Normal Mode automatically commands the necessary load factor with the longitudinal side stick neutral. Since Normal Mode also ensures a neutral spiral stability up to 33 deg bank outside of High Speed Protection, you can maintain a coordinated level turn with side stick completely neutral.

Beyond 33 deg, longitudinal stick neutral no longer commands the necessary load factor for horizontal flight. Therefore, you would need to have aft pressure. Furthermore, there is positive spiral stability, which means non-zero lateral pressure is also required to maintain the bank angle.

For more information, you could consult: source 1 and source 2.