Instead of researching if the earth is flat, research how an airplane keeps the same altitude.
Whenever a plane wants to stay at lets say 25k feet, they always have to set the nose up a bit. So a plane has to consistently go up to stay at the same altitude. The reason why is because the earth is round. If the earth was flat, a plane could remain flat in the air and not lose altitude. The fact that a plane has to consistently go up to keep the same altitude is proof the earth isnt flat.
Now if yall flat earthers take this and say every single pilot and airplane engineer in the world is also a part of the flat earth conspiracy, then there aint no way to help yall stupid motherfuckers.