At bare minimum you need need to have unlocked the
Grapnel Boost MK II, although the higher upgrade levels may provide you with more speed for this trophy attempt.
You'll want to start at street level and then use your Grapnel to shoot a corner of a building or some other object above the street levels. Use your boost to shoot up and over whatever object it is that you choose to use your Grapnel on, transition into a glide, then dive straight down towards the street, level out before you hit the ground, and then try your best to stay low as long as possible without breaking your glide. You'll want to pull up just a little bit in order to prevent yourself from losing altitude and touching the ground. You'll need to stay at least 10m from the ground which can be a little tough to estimate, but I found that as long as you below the top of the street lights, you'll be fine. The trophy will unlock upon landing.