Does an iron farm have to be in the air?

Does an iron farm have to be in the air? The actual direction of the shape can be whatever you want, but the layout matters, and there has to be air in the four corners of the 9×9 square space. The next way is how they spawn in villages. Villagers can summon an Iron Golem when they are panicking or gossiping.

The actual direction of the shape can be whatever you want, but the layout matters, and there has to be air in the four corners of the 9×9 square space. The next way is how they spawn in villages. Villagers can summon an Iron Golem when they are panicking or gossiping.
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