I’ve never used a screen protector on an iPhone and, since the 6, I’ve only ever used the leather case.
looking at my old 6, under direct sunlight at the exact angle, I can see a couple micro scratches.
My Xs Max had a couple micro scratches when I turned it in to upgrade to the Pro Max. Again, if I looked at in the exact sunlit condition in order to see it.
I’m sure if I look at my Pro Max super-duper hard, under direct sunlight, at the perfect angle, there may be one there already. If there is, and I happen to see it, I assume it’s the coating. Whatever.
I’m also an adult who knows because I don’t use a screen protector that this may happen, so I just enjoy my phone and I don’t worry about it.