if the earth was square then it wouldn't spin as easily causing a flux in temperature creating extreme temperatures and extreme weather also. The moon would have a chance of hitting the earth every day. If the earth was smaller the moon might fly a away causing the tides to go weird and be unusually violent waves
If the Earth was a square, it would no longer have any gravitational pull on us and we'd all die from the lack of gravity. A square is a two-dimensional object with a height and length and no volume meaning that no mass could possibly exist since mass is volume times density. If the Earth were a square, we would all be standing on a two-dimensional plane. without the gravitational pull of the Earth, the Atmosphere would dissipate and Everything flies into the sun or outer space, we die.