My property slopes up 50' in the far corner and there are 30' poles & wires over there.
If I always want 50' safe clearance above the highest obstacle, should I fly at 80' or 130' above Home, as shown on the controller?

Given your other post I have to ask have you read the drone's manual?
All heights used by the drone are relative to the take off point, therefore the necessary flight height depends on where you take off.
Take off from the low point and the hight required to clear the poles would be '130ft'.
Take off from the high point and the required height would be 80ft.

Hi there. Thanks for reaching out. As Sean-bumble-bee mentioned, it would depend on where you take off. The height showed in the DJI Fly App is relative altitude, which is calculated from the ground at the time of take off. Please reach us back here should you have other concerns.