Everyone has a specific plane based on their anatomy. A basic test for plane is to measure arm length (when measured from tip of your right index finger to tip of your left index finger when arms are out stretched parallel to the ground and your chest) vs. height. If your arms are longer than you are tall, typically you will fit into a more vertical swing plane, like Davis Love in his prime. If your arms are equal to your height you likely will fit a mid plane. That is where your lead arm will appear to be roughly parallel to your shoulder plane/tilt at the top of your swing. If your arms are shorter than your height you should trend to a flatter plane. Like Matt Kutcher whose lead arm never gets as high as his trail shoulder in the backswing.
All of these have some variability and deserve to be tested. Mid plane could be a little above or below the shoulder plane. I believe this is a complicated subject may well need to be addressed by a golf professional in a lesson. That is how I determine where to lead a student.