Dear @jumia, If you’ve heard "many things" about the length of power cables, you may be reading too many audio boards! 😉 There really isn’t that much to say!
If this is an effect at all, it’s vanishingly small compared to things such as speaker and component selection, speaker and listener positioning, acoustics, subwoofer positioning and integration, choice of listening chair, and so on. And the more subtle of those are absolutely swamped by variations among recordings.
As a rule, one could do far worse than "long enough to reach the wall outlet."