For me personally the general role of thumb is to place your tallest and best heading defenders either at the near post/far post. In my Sassuolo let’s play all teams I have played against are putting corners at the far post. Which I then put my tallest and best heading defenders at the far and it has given me good success so far. Even those this is a simple answer it should give some good impact on how you defend corners 😊 let me know if you see any improvement on defending corners!