Yes ingrown hair bumps do tend to go away on their own without any treatment within a few weeks.
However you can apply some apple cider vinegar to the ingrown hair bumps to help the ingrown hair bumps go away sooner and to help your skin look better.
When I had ingrown hair bumps I would apply apple cider vinegar to the ingrown hair bumps using a cotton ball and then let it dry and then wash it off.
I let the apple cider vinegar sit on the ingrown hair bumps for 15 minutes and then washed it off and repeated the process 3 to 4 times per day until the ingrown hair bumps went away which they did within 4 to 5 days.