Actually…. More knowledge, more facts & more powerful mental skills don’t give any clue away about the level the soul is operating at at all: only about the strength of someone’s mental body.
If you want to know more about maturity of souls, you have to look at different aspects.
Someone with higher consciousness has access to higher energy planes – and this can easily be seen or felt. Because tapping into higher frequencies places can only be done with heart.
So the signs of mature souls, someone who can enter higher realms, are simple: compassion, joy, responsible care, understanding, freedom, gratitude and humor are dominantly expressed.
The more willingness to care, natural responsibility and appreciation someone feels for life- the more you can tell that someone reaches high levels of soul growth.
They are not focused on external power, because they are fulfilled from within. And they know that love inside is the ultimate power. Millions times stronger than the illusion of external control.