Associating a feature with a different axis reference system will change the axis reference system for spatial data stored with the feature or with all of its observations. Note that you can only change to an axis reference system, that is based on the same axis. The change can be done in two different two ways.

Changing without transformation: This will change the axis reference system without transforming the stored spatial data. I.e it will only change the meaning of the stored spatial data but not its values. The real world position of stored spatial data will change.

Change with transformation: This will change the axis reference system and will transform all spatial data to the new axis reference system. I.e. the real world location of the objects described with the spatial data will not change but the spatial data will have different values and is expressed in another axis reference system.

Note that the transformation of spatial data might introduce rounding errors, i.e. changing back to the original axis axis reference system will usually not produce exactly the same spatial information.