Use this property to set the initial font size on MacOS Target platforms for the default Style.
This property has no effect in runtime, that is its only intended for usage in the property browser.
After setting this property then you will not see any changes until the window has been re-opened.
In StyleGrid, each cell can have one instance of a StyleGridStyle attached to it, if no instance is attached to it then the StyleGrid's default style is used to render the cell.