Trackmania

If you have the paid subscription, the track of the day for 07 September 2022 will unlock this at startup, confirmed in the comments.

Playing the Royal mode will unlock this for you if some of the tracks are in the sky, though as tracks rotate in and out of the pool, there might not be any available at the time. Worth playing a few matches of it to check.

Build height restrictions in the track builder will prevent you from easily unlocking this in that mode (and it's immensely tedious to use on console, and crashed on me more than once). But if you must, open the expert editor:

If you have the paid subscription, the track of the day for 07 September 2022 will unlock this at startup, confirmed in the comments.

Playing the Royal mode will unlock this for you if some of the tracks are in the sky, though as tracks rotate in and out of the pool, there might not be any available at the time. Worth playing a few matches of it to check.

Build height restrictions in the track builder will prevent you from easily unlocking this in that mode (and it's immensely tedious to use on console, and crashed on me more than once). But if you must, open the expert editor:

I found that the track build from Wyvern's guide actually works for this achievement.

What I did is I started up the Expert track editor, positioned my track placement 5 units below the maximum build height, placed a start at one edge of the arena, placed super turbo boosts (the red ones) almost up to the other edge, left a one block space and placed a smooth straight-to-wall transition (tech wall platforms - transitions) at the end. A finish is required to validate your track. And that can be placed either in mid-air or on the ground. Reaching a speed of 999 kph before you hit the ramp should guarantee the achievement. But if you find that this isn't quite happening (possibly due to your track not being long enough), you can tilt left and right to go in a light zig zag so that you cover more distance on the track. This should guarantee that you hit 999 kph. After a little trial and error, if you did this right, you should have the achievement pretty soon after you reach your maximum jump height.

Edit: As Wyvern suggests, you can lower your track height and use a more gradual straight-to-vertical transition if you find that the slope piece causes you to lose too much speed, but I found this unnecessary as long as you have a way to hit 999 kph.