This datapack is relatively simple..

All it does, is when you respawn at the world spawn it will drop you from the sky, 400 blocks up from your respawn point.
You will be granted immunity to fall damage for roughly 30 seconds, so that you do not end up in an endless loop of dying over and over.

By default it will also change the worldspawn on installation, increasing the area you can respawn in to 10k blocks.

This gives some variety to the area you see rapidly approaching you from below.

I would suggest using some form of method of invalidating the bed, as this only takes effect when you do not have a respawn point.
This does not affect respawning at your bed/respawn anchor at all.

I recommend using this with Unreliable Respawn Minecraft Data Pack (planetminecraft.com)
Or another datapack that affects regular spawn points in some way. Otherwise, you won't really see much of this datapack beyond an unlucky early game