I do not see keychain option in icloud

To confirm, you have 2 factor authentication (not 2 step verification) enabled on your Apple ID, and you have a 6 digit passcode on your phone. Can you log in to https://icloud.com using your Apple ID?

Do you have a company email account on your phone? Is the phone under Mobile Device Management? To check go to Settings/General, scroll to the bottom and look just below VPN for either Profiles or Device Management, and tap on it if it exists.

You must have 2 factor authentication enabled on your Apple ID to use Keychain in iCloud.

Open Settings. Tap on your name at the top. Tap on iCloud. You don’t see Keychain, just below Siri and above iCloud Backup?