Yes, the cat 6 is located in a electrical receptacle under my soffits.

You can buy various types of blank metal covers for standard boxes, and you could drill into them and provide a solid mount point for the camera bracket. You could also drill the box cover for one of these jacks to connect the camera https://www.amazon.com/Waterproof-CAT5e-RJ45-Feed-Thru-Coupler/dp/B00CULLAWE . However, there are other options.

Since its low voltage wiring, you could use a standard cover plate with an RJ-45 jack, and then mount the light on the soffit next to to the box. With low voltage wiring and the jack mounted horizontally under a soffit I don't think moisture would be a problem with a standard plate/jack. If you then mounted the camera bracket next to the box it would make it easy to remove the light or remove the box cover separately to check the wiring.

Bruce

I think the OP wants the box to have 120V wiring in it (he said 2-receptacle box). Is it OK to have LV and 120V wiring in the same box? Use a divider inside the box? I have a similar issue, which is why I am asking this.

mtvhike it's a 2 receptacle box but it's only going to have a cat 6 cable in it. I just wanted a way to mount the camera directly to that receptacle.

In that case, simply drill appropriate mounting holes in a blank metal plate. If you can make all your connections inside the box, that would be best. Get a waterproof box.