Imagine you are lying on a beach and looking at people around you. From this low position, your eye-level/ horizon is at the same height as their lower legs. The further away, the smaller they become, but again and again with their lower legs on our horizon.
Exercise 1: Try this low viewpoint with two or more figures at different distances. For each figure, ensure that the ratio between the area above and below the horizon remains roughly the same. In the example, I used the simplest possible “sleeping bag figures” with a slight shadow on the ground.
Exercise 2: This time you’re standing on a dune, watching people walking on the beach. The people are all below your high horizon/eye level. The further away, the smaller they become and the closer they are to the horizon. Try this high vantage point with two or more figures at different distances.
Exercise 3: This time you are walking with the others. In this case you draw people (who are in reality the same height as you) with their heads at the same height as your horizon/eye level. The further away, the smaller and the closer their feet to the horizon but their head always remains at your eye level. Try this with two or more figures at different distances.