Password Autofill is binary; this function is either ON or OFF.
Recent major versions of iOS/iPadOS allow you to select one or more credential sources for Password Autofill - dependent upon Apps currently installed. Potential Password Autofill sources include iCloud Keychain, Microsoft Authenticator, Google Chrome, Firefox Lockwise etc. (this is not an exhaustive list).
Whilst the Password Autofill function can either be enabled or disabled, the function is otherwise independent of your iCloud Keychain and/or other credential repositories. As such, whilst disabling Autofill will inhibit the ability to automatically enter website credentials, you can continue to manually access, create and edit credentials using your chosen password manager App(s) and Keychain.