Watch this video to get started:
www.youtube.com/watch?v=KNxcgGpnn8Q

(alternatively, you can use the instructions below)

TO PRE-EXISTING SINGLEPLAYER WORLD

Click on the Download button, it should redirect you to a Mediafire page.



Download the zip file.


Now go to your .minecraft folder, go to saves



Then, click on the world you want to add it in, go to the datapacks folder, and paste it in (unzipping is optional)





TO A BRAND NEW WORLD

Open Minecraft, Click on Singleplayer




Click on Create New World

Click on Datapacks, Click on Open Pack Folder

Drag and drop the Datapack File inside the Data packs Menu

Click on Done, and create the new world

TO ADD TO A SERVER

Open the server container

Go to the world files, Find Datapacks, and drop the zip file inside.

Log onto your world/server, and make sure you have OP/Cheats - You just need perms to set it up



Run this command in chat: /datapack enable "file/Fly Mode Datapack"

Then, run /function fly_mode:start

Now, use /function fly_mode:fly to enable fly mode for yourself, and use /function fly_mode:no_fly to disable fly mode for yourself.

When you enable fly mode, you will receive a warped fungus on a stick named "Right Click to Fly", I think that's self explanatory.

Fly mode should be easy to control, once you get a hang of it. Right click the fungus to fly (you can spam it), and don't worry about fall damage.