I have searched for an answer for in what way are electric and magnetic fields perpendicular, but I only found mathematical explanations speaking of orthogonal vectors and Maxwell's equations and vector products.

I was wondering, in what sense, physically speaking, are the electric and magnetic fields perpendicular to each other?

I have seen that electromagnetism is the result of relativistic effects at the quantum level. Is it that the rotation of an electron creates these effects, and magnetic effects are related to the polar axis spin of the electron, and electric effects to the equatorial rotation of the electron? And this is why the two fields are perpendicular to each other?

And why from one frame of reference, you can see an electric field, and from another frame of reference you see a magnetic field - because it depends on your angle relative to the electron's motion?