The Solar Plexus is called the second brain or mid brain. For a yogi, the solar plexus is larger in size.
Scientists have also confirmed this. It is small in a person who does not do yoga and meditation.
A yogi who does meditation and yoga has a larger solar plexus. When solar plexus is larger, one is creative and generous. When it is smaller, one is jealous.
For developing solar plexus, one must do Padma Sadhana