NA rear bumper removal

Today i went for a used NA rear bumper and after consulting some you-tube tutorials for the fitment i found out nobody mentions the holes (10 large 1 small) on top of the bumper, only the 3 side bolts and the ones below are mentioned…So, what are they for? And if used how to get acces? removing taillights and the panel between?

You remove the bumper cover and bumper reinforcement in one. The clips are to attach the bumper cover to the bumper reinforcement. You need to remove the bumper to do that.

Thx, that makes sense . This was one of the tuturials i cheked out and it was not obvious to me (the clips/reinforcement).