When your speaking slot you are given is longer than usual, you should adapt your content and structure to the new time frame. Here is how I did it, when I stepped up from a 7- to a 20-minute speech.
When I trashed a boring script and re-wrote my informative speech, I realized how I could make it more appropriate for my style and more engaging for the audience.
I don’t feel comfortable with informative speeches. When I speak, I prefer to use an entertaining tone and some humor, but I always wonder if this style sounds credible enough when the main objective is to convey information.