Difference between Canon and Nikon image appearance?

I'm not trying to ask if one is better than the other, but instead if the cameras give different looks in regard to color renditioning and clarity. As well, are these differences that become irrelevant once post processing is done?

Not sure

There used to be a "common knowledge" that Canon gave warmer images out of the camera, while Nikon gave a more natural look. It was bogus then, and it still is. The difference is in the default settings of the camera out of the box… Canon set their cameras to give a warmer look, while Nikon set their cameras to give a more natural look. Either can be set to do both, or something completely different. This applies to out of camera JPG images.

With post processing of RAW images, none of these settings matter.

Both good cameras. Who is holding the camera will make the biggest difference. Lighting and composition are key skills with any camera.

Yes, there are subtle differences. Yes, of course, they are irrelevant after you manipulate them to your taste.

Yes, the jpeg default color rendering is set to a difference. Probably because some marketeer though it would sell more cameras. But, you can change the settings.

As for clarity, no known differences for the camera bodies. Clarity is mostly a function of the lens, and both companies have some excellent lenses. And their kit lenses are quite good, with no known differences as far as clarity goes.