Which effects does the setting of the opening scene have on the play macbeth?

The effect that the setting of the opening scene has on the play Macbeth is that:

It creates a sense of mystery and gloom.

Explanation:

In the opening scene, the conversation among the three witches is shown. They are seen to be discussing the next place where they will see each other again. The witches departed after saying that "fair is foul, and foul is fair." This introductory scene creates a sense of mystery and suspense as to what would be the following scenes bring. Also, the dark and gloomy atmosphere is been set up by the witches who actively set up the mood of the play.