Due to Earth’s curvature, a distant but still visible object is slightly leaning away from an observer. However, the angle is minuscule and undetectable to any observer.
After being shown photos showing the obstruction of a distant object due to Earth’s curvature, flat Earthers would often shift the topic by pointing out that the tilt due to Earth’s curvature is not apparent in those photos. In reality, the tilt is too small and not visible to our eyes.
Earth’s circumference is about 40030 km or 24874 miles. So, to have an angle of 1° away from an observer, an object needs to be at 40030 km/360° = 111 km or 69 miles from the observer.
However, at 111 km (69 miles), more than 700 m (2300 ft) of the object is obstructed by Earth’s curvature, provided that the observer is 2 m (7 ft ) above ground.
Currently, the Burj Khalifa is the only human-made building that is possible to be seen from 111 km (69 mi) on ideal conditions. And even then, only the upper parts of it are visible.
An angle of 1° away from an observer is a small angle. Our eyes will not be able to distinguish a straight-up object from another with an angle 1° away from an observer. It is not realistic to expect anyone to be able to observe the tilt caused by Earth’s curvature.