This poncho pattern is based on the Eloelai Go Anywhere Cover-Up.The design is neat and lends itself well to a poncho as it has a good drape to it.
The measurements in the pattern are for a size 14 (UK) who is 5’8” tall, but I have included notes on how to adapt the pattern if you are smaller. I would suggest that instead of decreasing - as I suggest for a smaller size - you might like to try increasing by the same amounts, should you wish to make a larger garment.