Garritan World Orchestra Playback Template

Is there a Garritan World Orchestra playback template for Dorico 5?

No: but I’d recommend reading my documentation for working with Garritan in Dorico, which you’ll find amongst the downloads here.

Use the Notation set of instruments, and follow the list of keyswitches on pages 54-60 of the World manual. Bear in mind that the keyswitches will be in the lowest octave of the MIDI range (p. 26), so not C1, but C-2 (at Middle C = C3).