A monologue should be spoken with varying intonation, pitch, and rhythm to create a sense of drama, urgency, and emotional connection with the audience. A monotone delivery would flatten the impact of the monologue and make it difficult for the audience to engage with the character or the story being told.
Additionally, a monotone monologue could quickly become monotonous for the audience, causing them to lose interest or even become bored. Therefore, while possible, speaking a monologue in a monotone is not generally advisable or effective in storytelling or performance.