Samples are available within the Starter Samples project available on the Starter Samples Github repository. The folder Assets/StarterSamples/Usage contains a scene named SceneManager which demonstrates the most important features and concepts in a single scene. Additional sample scenes for individual features or concepts are also available. The former provides a quick overview of Scene capabilities, while the latter are good starting points for people who want to learn about specific features.
The documentation for all Scene samples in the Starter Samples can be found in Scene Samples Overview.