A charged rod is not a point charge. Every little piece of it pushes on you from a slightly different direction, and to find the total field you have to add all of those up. This walks through that in four steps: set up the geometry, take one small piece, split its field into components, and see what survives when you add them all together.
Choose a positive or negative line charge. Set the two angles α and β with the sliders — these fix how far the rod extends above and below the point you are measuring at. Both snap to the standard angles: 0, 30, 37, 45, 53, 60, 90. A negative β puts the point below the end of the rod. Step through the four stages with the arrows, and in the middle steps drag the small element along the rod.
The point P sits a fixed distance from the rod. Take one small piece dQ and the sim draws its field dE, then splits it into dEx and dEy. Step to the last stage and the two totals appear as formulas: Ex = kλ/r (sin α + sin β) and Ey = kλ/r (cos α − cos β). The panel shows both angles and both components.
P cannot be moved. The distance from the rod is fixed. The field values are normalised, so k and λ appear in the formulas but not as numbers you can change.
You should be able to say why the two components have different formulas, and what happens to Ey when α and β are equal.