According to Zhu Wanhao's understanding of Dongyuan Continent's cultivation system and some speculations, if nothing unexpected happened, the realm after transcending the tribulation should be the True Immortal realm.
The so-called True Immortal realm, as the name implied, was to become a true immortal. They had an unimaginable lifespan and controlled unimaginable power.
Genuine Immortals had immortal bodies, immortal vitality, and primordial spirits. They were three in one, far superior to cultivators in the human world and transcended another realm.
If there were no accidents, there might be Earthly Immortals and Celestial Immortals above Genuine Immortals. However, even Earthly Immortals and Celestial Immortals should not be involved in the cultivation of rules. Only when they reached a higher realm would they be involved in the cultivation of the power of rules.