As noted https://medium.com/amazing-article/19ceea5e440e, pressing ± when zoomed in or out will temporarily zoom to actual size (as long as you keep the key pressed).
Thing is, not many people can “reproduce" this feature.
Just out of curiosity, can you?:)
ps: Here's a video to showcase the feature: https://www.youtube.com/watch?v=tdMjJqYtVAk