This sandbox game. It's not trying to ruin your fun, but it does make things a little more entertaining if you want to go a little bit faster thanks to reduced air density.
With so many Minecraft mods out there in the world, finding ones that work for you can be tough. Maybe you want an overhaul mod of sorts like this Superflat biome generation mod is a good shout. However, if all you want to do is tweak how flying around feels when using an Elytra, then this is the mod for you.
The Elytra Aeronautics mod just wants you to have a bit more fun when zooming around in the sky. To manage this, it makes it so that you go faster the higher you are, because that's how it works in real life due to the change in air density, and therefore the lower resistance. It also adds extra cloud layers so that you can see where your speed will go up or down. Finally, both of these things can be customized too.
You can do things like add in more cloud layers for different changes, or make yourself faster or slower as you please. It's a fun Minecraft mod that makes late-game traversal a bit more interesting, and while it's not going to change how the game feels completely, it's still an enjoyable shift.
If you're hoping to find something impressive while zooming around up there, have a look at our list of the cool Minecraft house ideas to check out too.