Make sure Wi-Fi and Bluetooth are turned on for both iPhones
Keep both iPhones close together
Connect the iPhone with the Wi-Fi password saved to the network
Unlock both iPhones and keep them on the Home screen
On the other iPhone, open Settings
Tap Wi-Fi
Select the same Wi-Fi network
Wait for the password sharing prompt to appear on the connected iPhone
Tap Share Password
Tap Done
If the prompt does not appear, restart Wi-Fi on both iPhones and try again
Make sure both iPhones are signed in to iCloud
Make sure the contact is saved in the connected iPhone’s Contacts app