I ran into the same issue and this answer (from Google's AI response) is what I have found so far. I have not tried it out yet, so I don't know if all the functionality from Flutter Outline is still available.
Based on the information available, the Flutter Outline window has been deprecated in recent versions of Android Studio and IntelliJ, including version 2024.3.2. This means it is no longer the primary way to view and interact with your widget tree.
However, there are still ways to access the functionality previously offered by the Flutter Outline:
Structure View: You can use the Structure tool window found under View > Tool Windows > Structure. While it's in a separate window, it provides a hierarchical view of your project's structure, including widgets, according to GitHub.
DevTools: The Flutter plugin for JetBrains IDEs has integrated DevTools, which may include features that replicate or replace the functionality of the Flutter Outline.
Editor-based actions: You can still use shortcuts and context menus in the editor to manipulate your widget tree. For example, you can right-click on a widget to access actions like wrapping it with other widgets (e.g., Column, Row, Center).
In summary, while the dedicated "Flutter Outline" window might not be present in Android Studio 2024.3.2, its functionality is still available through other means, primarily the Structure view and potentially through DevTools integrations.