So this is still a relatively new feature that a lot of people don’t know about. You can create a note and lock it with a passcode in just a few quick steps.
I use this a lot for my children’s passwords and other not-so-sensitive information. It may not be as secure as two-factor authentication, but at least it’s better than storing the info in Contacts which is what I used to do. Note: You will select one passcode for all Locked Notes—be sure you remember it!