Take a good long look at the picture below.
Often we see photos of people holding the tip of Eiffel Tower or leaning against the Leaning Tower of Pisa or even gobbling up the sun. That is what forced perspective is all about. We use the camera settings in such a way that the difference between the foreground and the background is intentionally blurred.
Now look at the photo below.
You notice that all the objects are in different planes, yet in the first photo they seem to be kept side by side. That is the beauty of forced perspective.
Go have some fun with the optical illusion!
Last time, it was Focus Stacking.