The introduction in Chapter 1 is actually relatively clear.
First go through the four levels of Quefan.
Then comes the ninth level of true energy realm
Then there is the third level of the spiritual realm
Then there is the fourth level of the Golden Core Realm (the fourth level is very special)
Then there is the fourth level of Nascent Soul Realm (the fourth level is very special)
(vacancy)
True Lord (short path, the name of the realm will not be revealed yet)
Tianzun (Tripod of Heaven and Earth, Da Dao, the name of the realm is not revealed yet)
As for the relationship between the fourth level of the Nascent Soul and the True Lord, we can only say that there is a very special path. To say it would spoil the setting and outline. As long as you know that there are other divisions in the middle, the fourth level of the Nascent Soul is not just about meditating and practicing.