apologies. NHFS (high school)
It's my understanding that the penalty yards should be enforced from the original LOS. If the yards gained on the run are to be factored in the play has to stand and the down "counts."
You did not state whether the foul was committed before the play ended or after the play.
You implied that the play was a running play because the basic spot you stated was the end of the run.
If the foul occurred before the end of the down, and if you have a 2022 NFHS Rules Book, the reference is 5-2-2b.
If the foul occurred after the play ended, yes the down will "count" and then the penalty yardage will be administered.