Minecraft Legends

Campaign maps are randomly generated, so the spawn location of the big beak and brilliant beetle can be random.

Once you've found either of these mounts and are riding them, find the highest point of the map that you can (Typically the mountains of the snow biomes) and once you jump off, press and hold to maintain gliding and hover over the lowest points at all time to prevent landing. Your achievement will not pop until you land, even if you surpass the 30 seconds, so try to keep track of your glide time.

I found the Mount Big Beak in the northwest section of the map, a little northeast of the Swamp Village

Big Beaks are brightly coloured birds that when you jump, you can hold down (or whatever button you have for jump) and you you will slowly float to the ground

In the same area where you find the Big Beaks, there are really tall snowy mountains, climb to the very top and you should see some Bouncecaps (red and white mushrooms that spring you high into the air when you jump)

Using your Big Beak, jump of a Bouncecap and hold and try and stay in the air for asking as you can, 30 seconds should be easy to do

*EDIT*

I didn't know the maps were randomly generated for each player, apologies

In custom game in versus mode you can:
set global gravity to 10% (the lowest possible) on the WORLD tab
fast feet, high jump and invulnerability to on on the PLAYER tab
Big Beak or Brilliant Beetle to on under Mounts on the PLAYER TOOLS tab

The match can be started with one player

Once loaded in you probably want to wait for the piglin attack and kill them, then on your map you can place a marker where the Big Beak or Brilliant Beetle are, I went for Big Beak as it was near a high peak on my map

Jump off a high point and hold to glide. I was gliding for a few minutes before I gave up and landed and the achievement popped immediately

I recommend doing this with the Brilliant Beetle as it can climb walls. This mount can be found randomly in your world, then you want to head to the Jagged Peaks area of your world. Climb the tallest mountain, jump off, and hold the jump button to glide. This will pop once you land.