Well I can tell you how I did it, if any of your apps offer to let you have more control. I extended the canvas 10px all around and filled it in with white, then extended the canvas again 100px and filled it with black. And I put all those commands in an action, so it is now just one click for me.

Hmm if you are running Windows, you might try Gimp (https://www.gimp.org/), which is the opensource photoshop clone. I'm not sure if it will let you do what I described above (as I've never used it)

On iOS there is another photo app that gives decent frame/border options. It is Phototoaster. I'm not sure if there is a version of it for Android.

I'll let you know if I think of more thruout the day.

Have a good Monday!