AgileBits has a 1Password update that supports the AutoFill feature of the iOS 12 password. Now you can use 1Password on your iPhone or iPad to automatically enter user names and passwords, just like Apple's own keychain. If you have to log in to a website for once, iOS 12 can automatically fill the fields with the information from your 1Password database. Once the 1Password update is installed, you must enable Autofill in Password of iOS 12; Account settings. You can find the update in the Updates section of the App Store app.
: 1Password adds iOS 12 password AutoFill support