The outline is a guide, as brief or detailed as you like. Don’t be afraid to expand and revise the outline even after you’ve started writing. You may find that once you start writing, an action will prompt you to think of another event or action that needs to happen later in the story.
even if you are not sure, still include the scene in the outline. It is better to write it now and then check it later, than not to consider it at all.