A "Ren Trickshot" is basically perfomed by doing a classic trickshot which you can do in every game with weaponry such as snipers, and semi auto rifles.
To perform the "Ren Trickshot" you'll have to jump off something and do a 360 before you drop down/after you land.
If you're in a "fall to your death" situation you will have to do a 360 right before you jump off because one of the options will obviously be striped away.