why is there a password app on my phone when I didnt download it
After the update I installed, the app appeared and the password function is not in settings
You are correct. Sounds like you are not aware that things have changed in iOS 18.
Which is easier for you?
Tap Settings and scroll down and look for Passwords
Tap to open Passwords
or
Tap on the Password app....which you have moved to your "main" page.....to open Passwords