I'm playing Civilization 6 and I would like to see a list of completed world wonders.
In the Antarctic Late Summer Patch, March 2019, Firaxis added a Search functionality into the game. In the development videos it was stated that this functionality was being included within the base game as well, so purchasing Gathering Storm should not be required. Using this feature you should be able to search for a term like "Wonder" and in theory it will allow you to cycle through the ones that have been created. Worst case you could search for them by name.
This strategy was mentioned by Carl during the video as a practice that you could do prior to committing hammers to producing a wonder, you could check to see if someone else had already started it.
Also I think this might only apply to tiles that you have had previous visibility to, but I would have to double check that mechanic to be certain.