One of the most used way to extend the end of a worship song is with the use of the plagal cadence. In fact, it has been used for years as the ‘A-men’ ending of hymns in traditional church music.
To understand how it works, you should know what the I, IV, and V chords means. This is briefly explained in volume two of the Worship Guitar Class course and fully taught in our Music Theory course for Guitar. You can see a brief teaching on the plagal cadence in the following video. It starts at around the 1/3rd mark, in the video below.
Basically, the I, IV and V chords are chords built on the first, fourth, and fifth notes of any given scale, or key. In the key of ‘A’, the chords are ‘A’, ‘D’, and ‘E’, or ‘E7’. The V chord is often changed to V7. The plagal cadence is ending with the IV to I chords. For example, ‘He’s Got The Whole World In His Hands has just two chords, ‘A’ and ‘E7’. The song is based on the I and V7 chords. (A-1, B-2, C-3, D-4, E-5). With a plagal ending, the last line would change to:
(A) He’s got the (E7) whole world in His (D) hands. … (A)
Instead of going straight to the ‘A’ chord, the chord ‘D’ is playing when singing the last word ‘hands’ and then ‘A’ comes one or two measures later. The music for the song is at the website, http://www.worshipguitarclass.com/guitar-video-dvd.html.