AbsoluteOptions

AbsoluteOptions[expr]
gives the absolute settings of options specified in an expression such as a graphics object.

AbsoluteOptions[expr, name]
gives the absolute setting for the option name.

AbsoluteOptions[expr, {name₁, name₂, ...}]
gives a list of the absolute settings for the options name_i.

AbsoluteOptions[object]
gives the absolute settings for options associated with an external object such as a NotebookObject.

AbsoluteOptions gives the actual settings for options used internally by Mathematica when the setting given is Automatic or All.

If you ask for AbsoluteOptions[NotebookObject[...], name] the kernel will send a request to the front end to find the result.

Find the explicit values of PlotRange->Automatic: