Hi. Unfortunately, I'm not really sure which photo corners you are admiring without seeing the LO's in question, but there are several ways to get a photo corner look.
Of course, you can buy them, punch them, stamp them or make them. I referenced quite a few products that can help you produce looks you might have seen.
Also, one very easy method to make them out of simple paper is to cut a square shape. Fold it in half. Then, with the fold at the top, airplane fold the sides in to create a triangle shape. Just flip this over, and the top layer will be the part of the photo corner that shows above the photo. The rest can be secured underneath.
You can use corner punches for those! I have a few Fiskars corner punches, they're not exactly photo corners, but they have really pretty detail and u can punch the corners of the paper you are going to use to mat the photo with.
Or I also take brads and put them in the corners of the photos once they've been matted (or not.)
I LOVE it when I use a pretty flourish style rub on, on one of the colors, instead of using photo corners, that's another alternative that turns out BEAUTIFUL!