The Property Growth / Depreciation Rate preference is the initial, default rate at which property, at least once purchased, will increase or decrease in value. A negative value could be entered in cases where a depreciation rate is deemed appropriate.
The setting can be found in Plan Settings, in the inflation/growth section, it will apply to the client case that you are presently viewing. This assumption can also be edited on a per-scenario basis within the client case.
For a future property purchase, the Inflation Rate is used to compute the future value of a property when purchased.
This default setting can be overridden for any individual property or asset in the plan by adjusting the Growth Rate on the basics screen of the Property.
How to add custom plan settings for your entire subscription.