My Citroën BX has various ride heights since it works on hydropneumatic suspension.
I'll go ahead and answer my own question since I recieved some help from a Xantia driver.
The lowest syspension setting turns off the system and leaves your car with 0 suspension wich is highly unrecommended.
It's inteded for servicing and liquid flushing.
On the other hand higher ride heights can be used to drive although the highest setting is exclusively for low speeds and clearing obstacles.