Realms

Mortal Realm:
An extrodinarily huge world filled with trillions and trillions of people, but only a couple million cultivators. Seen as gods due to the huge strength disparity between cultivators and mortals, Cultivators often stop pursing the path after getting to a certain rank, choosing to become kings and emperors.

Seemingly because of just how large the world is, the amount of Qi naturally generated is extraordinarily low and extremely impure, forcing people who do chose to cultivate to slog through numerous extra ranks. Whilst the strongest person in that world is merely of the Master rank.

With countless kingdoms and empires rising and falling all the time, the world is a chaotic mess of fighting and instability. A truly hellish place for anyone to live, including cultivators, nonetheless mortals.

Immortal Realm:
A world half the size of the mortal one, the Immortal World is filled with hundreds of billions of people, about half of which are cultivators. People born here have a much higher aptitude for cultivation do to the pure Qi and extreme abundance of it.

Having naturally spawning high-grade cultivation resources, the world is filled with powerhouses that could easily sweep away and conquer the entire Mortal Realm, perhaps giving a reason as to why people cannot descend to their nor can people ascend to the Immortal Realm.

With the strongest people being of the Sage rank, they all secretly control the world with the Three Empires that rule the world all working together. To keep the population low and themselves safe from potential powerhouses rising up, the three empires occasionally war with one another, whilst they also influence clans and sects to fight with one another.

Energetic Eternity:
The energetic Eternity is a world-less, lifeless realm of infinite size. Spanning on endlessly, it is filled up with every energy imaginable, including the common Qi cultivation system and trillions of different energies that have never been used or cannot be used due to them being too powerful.

Nobody knows of this realm and it is nearly completely inaccessible to prevent people from getting a hold of too much power.