You can open the quick panel in with the shortcut set in the addon preferences. It will only show up if you have switched to Layer Painter from Default. The default shortcut is Ctrl+Rightclick.
In the viewport tab you have options to change the hdri backdrop of the viewport as well as enabling Ambient Occlusion, Bloom and Screen Space Reflections.
In the tools tab you have options that help you quickly set up your viewport.
- Add Workspace: This adds the Layer Painter workspace, which is set up to work well with Layer Painter.
- Open 2D Editor: This will open the Image Editor to give you the option to paint an image in 2D.
- Reset 3D View: This will reset the 3D view to its default settings.
- Eevee/Cycles: This will set up the viewport to show the material in either eevee or cycles.
- Set 0/Set 1: This will set the background opacity to either 0 or 1.