If you are looking for a place where your Apple ID (or device ID) are stored so you can look it up. There isn't one. Not automatically. You need to store that somewhere manually, or remember it.
No operating system or service stores it's password in a readable format automatically. Apple's keychain is only for storing and using passwords for other services and accounts.
The iCloud password is used in a few different places, and would be better named as your Apple ID*. You use it to log into your iCloud account under your user account, which is accessed by tapping on your name in Settings at the top of the list.
You would also use the same password to sign into Apple's other services like Music, the App Store, and Apple TV.
With the recent update to iOS/iPadOS 16.2, Apple has enable signing into your iCloud services using the device password. To do this you'll enter your Apple ID when prompted. I'm not sure what or where the original Apple ID will be used after that other than when signing on in a web browser.
* It is possible to have different accounts/passwords for your Apple ID and iCloud. It is unusual. You would have had to do it on purpose. Creating and Apple ID or iCloud account will create both accounts at the same time with the same password unless you deliberately avoid doing so. You would not normally do this unless you were trying to share one of the two accounts with another person while keeping the other account private.