Make color_depth property for reuse

IPython/terminal/interactiveshell.py

@@ -288,7 +288,7 b' class TerminalInteractiveShell(InteractiveShell):'
                             include_default_pygments_style=False,
                             mouse_support=self.mouse_support,
                             enable_open_in_editor=self.extra_open_editor_shortcuts,
-                            color_depth=(ColorDepth.TRUE_COLOR if self.true_color else None),
+                            color_depth=self.color_depth,
                             **self._extra_prompt_options())
 
     def _make_style_from_name_or_cls(self, name_or_cls):
@@ -365,6 +365,10 b' class TerminalInteractiveShell(InteractiveShell):'
             'readlinelike': CompleteStyle.READLINE_LIKE,
         }[self.display_completions]
 
+    @property
+    def color_depth(self):
+        return (ColorDepth.TRUE_COLOR if self.true_color else None)
+
     def _extra_prompt_options(self):
         """
         Return the current layout option for the current Terminal InteractiveShell