World clock widget in Catalina

This is a general request that those who provide answers intended to help do not make assumptions that the person asking the question knows non-intuitive things. For example the first answer to "where is the world clock widget in Catalina" was "in the notification centre", assuming we knew where the notification centre was. The only place I could find a reference to notification was in the system preferences, and it was only when subsequent responders added the information that the notification centre was under some unlabelled icon in the top right corner that I was able to find the clock. Thank you to everyone who is helping, but please be aware that people unfamiliar with the changes in a new MacOS will appreciate you even more if they don't have to scroll past your contribution and many others to find a complete answer.