@Jan_Singer
Correct. It does not matter.
What matters is the trainer reads your pedal cadence and the trainer’s flywheel velocity to determine the real gear ratio i.e. physical size of the chainring and the cog size on the trainer. This happens ONE TIME when your Zwift avatar spawns in game, and sets the trainer’s resistance level to the middle of its range - this is the virtual 12th gear out of 24.
The real gear calculation does not happen again during your session. If you shift your front derailleur from the large chainring to the small or vice versa - the trainer does not reset you to the virtual 12th gear.