Where is my wi-fi password on my iPhone

Your WiFi password is set/configured on your WiFi Router. You must then enter the matching WiFi password on your device.

Whilst your WiFi passwords are stored in your Keychain, you cannot read-out the password that has been set. You can, however, share the password between your devices using AirDrop:

Share passwords securely with AirDrop on iPad - Apple Support

Hello~ Take a look here:

If you need help with your Wi‑Fi password - Apple Support

Set up iCloud Keychain - Apple Support

~Katana-San~