How do I see the Wi-Fi password option whiles am already connected to the network

Go to Settings -> Wi-Fi. Tap the circled lowercase i on the line for the network you want to see. Then tap the dots that are hiding the network password. You will need to authenticate to disclose the password.

This is a recent feature that may not be available in older releases of iOS.

If you are already connected to the WiFi what is the need for knowing the password is not clear to me. However, learn How to share your Wi-Fi password from your iPhone, iPad ...