How do you add keywords to photos on a Mac?

In the Photos app on your Mac, select the photos to which you want to add keywords. Click the Info button in the toolbar. In the Info window, click the Add a Keyword field (or the field where other keywords appear if you’ve already added some), then type a keyword and press Return to add it to the photos.

For More Information Please Refer: https://support.apple.com/guide/photos/find-photos-by-keyword-pht8d0ad5198/mac