My daughter tore a large rip in her favorite overalls (they already had a hole in the knee but this was a long vertical tear coming off the hole she wanted). I decided to try mending the tear and instead of trying to hide it, which I wasn't confident I could do well, to just make the mended tear part of some decorative embroidery. I think the final result turned out really nice looking!
I also did some backstitching around the edges of the hole in the knee that she wanted to keep just to hopefully stop it from widening or fraying even more. It's pretty difficult to see since I did it in white.
Well, I'll have to wait a few weeks and see how successful the actual mending part was, but in general I kept stitching past where the actual tear was, to try and reinforce the fabric a bit at the ends of the tear.
I'm my experience tears like that are hard to fix by just stitching the two sides back together - if it comes apart again it might benefit from a patch, which you could put on the inside if you want to keep the current look