So your metal post isnt rusted out but is leaning and a bit loose?
Your in luck the orioginal installer did a excellent job:)
Dig gently around post, straighten and backfill and tamp firmly!
Light poles arent meant to be structural. just self supporting.
If it had been concreted in theres little you can do. too big too heavy
too awkard to reset.
just straighten and tamp with foot. problem over.
plus you can move this pole if ever necessary,
concrete forget it.
I was given this advice by the salesman who sold me a light pole over
25 years ago.
that pole is still in use today, has been dug up twice once for sewer
work. A1 shape......