Depends on how you're using the CANOpen. In Cyclic synchronous position or interpolated position the master is calculating the trajectory. The position command goes to the object 0x60C1:1, which is the drive internal position command in counts/revolution (0x6063:0 for actual position). The only adjustment that can be done to this object is with FB1.PSCALE to shift the resolution. The definition how many bits are used per revolution. The rest up to the 32 Bit limit is the used for numbers of revolution. With this trick you can shift around the gearing but only in binary numbers.
If Profile position mode is used and the trajectory is calculated by the drive, the master is only commanding the target position. The position command object then is 0x607A:1 (0x6064:0 for actual position). This two objects can be scaled by the drive gearing ratio setup in workbench or by the objects 0x6091, 0x6092.