In the diagram there is no voltage divider action. The only change is to the effective resistance value as seen when measured across R26. Now, consider if the bottom end of R26 was grounded and there was an additional resistor Rx in series with R26, and the signal was being fed into the circuit via Rx. Then there would be a voltage divider action at the junction of Rx and R26 which would be modified when R27 is switched in. That would give you the ability to switch the output level between two values.
The circuit pictured may act as a voltage divider (or not), but only in the context of other components in the circuit.