You just need to use file output node in compositor pane. And what they called render layers is now View layers I believe. Mist etc, they call it "passes" or "AOV"s, You don;t have to save then manually either . Use file output too. Pay attention to color managment. What you see with viewer node is linear usually and png…
Without using the compositor and no output node.. blender is only saving on Render Animation and only what can be seen in the actual slot and view layer.. since.. .. i don't remember if blender saved on Render Image.. (using 2.49 up to 3.4 on debian linux.. 🤷) Except if you did choose use OpenEXR (Multilayer).. (but you…