[maxandre]

The wiki states "A fact of basic perspective is that the line of the horizon is always at eye level with the observer." What does this mean? Does it mean that the horizon is always horisontal with the eye?

[Tumeni]

Well, it doesn't "rise to eye level" at all...

[J-Man]

Just like sea level it's an impossibility to have eye level or sea level on a globe. The earth is a pancake and thus we can measure sea level  as constant with eye level.

[model 29]

it's an impossibility to have eye level

FlatEarthers seem to refer to "center of one's vision/image" as 'eye level', regardless of angle of tilt of one's eyes/camera.

or sea level on a globe.

Depends on meaning of the term, but even following the curvature around the globe, any one spot on a body of water is level.  (disregarding waves)