Is there any way how to have an IconButton in the AppBar and an IconButton in the Body the same column width? The splash radius should be default. Please have a look on a screenshot at the following link for an overview.
I'm not sure if this is the solution that you are looking for, because your question is not clear 100%.
By default IconButton are aligned to the AppBar actions. You can check it on this sample:
https://dartpad.dev/?id=0199904cac2a477c420efe473ed21319
The result is this: