How to tag people on iCloud Photos?

Solution 1:

To tag people on your IOS device you will require IOS 15. Go to a photo in Photos, drag up to see the metadata, if it has detected a face it will show the name or a "?" if it's a new person. Tag them and your good.

If you are on IOS 14 or earlier there is a workaroundto use the Photos.app in OSX and tag them there (info -> Add Faces), those seem to carry over to IOS eventually.

If the PC is running OSX, then photos are synced via iCloud photos to the Photos app. If it's running Windows, they you can download the "iCloud for Windows" app to have the photos synchronized.