“In a 5.1 system, your surround speakers are best placed to the left and right of your listening position. Aim them directly towards you for the best sound. If side placement isn't practical, place your surround speakers a few feet behind your listening position and face them forward. You’ll want your surrounds one to two feet above ear level to get the best sound effects.”

https://www.crutchfield.com/S-FBwUWhvkwVo/learn/learningcenter/home/speaker_placement.html