Corner posts should be buried deeper to the ground at least 2 3 of the entire length of the post compared to your line posts at least 2 feet.
Fence posts not in straight line.
When you lay out the perimeter of a fence you can do it the traditional way using strings or if you re a techie using a laser.
If the posts somehow end up in a non plumb situation you maybe can drive large wedges from pt wood in the ground next to them.
Posts not in a straight line don t forget gravel or small stones at the bottom of the hole.
Considering this your corner posts should be longer and if possible larger than your line posts.
Either way the very first step is to determine your property lines so you can stay inside them unless you live in a state that allows shared fences on the property line and your neighbor agrees to the project if you skip this step you might have to take.
For the extra couple bucks for the longer post and the extra couple bucks for the setter its well worth it 10 years down the line when the fence is still strong as ox and straight as arrow.
I d rather not dig out the thing because it s 2 5 feet in the ground in concrete.
Lack of light and a rush to finish the job before a thunder storm resulted in one fence post being slightly out of line about 1 1 5 inches.