But mesh is already straight across,
so adding risers would be harder if not impossible without redoing the whole thing...
....just need to support what already up.
You'll have to check the size of the kennel bars......if they are close, bigger or smaller, you can make it work.
Think now about how to separate parts of the coop for your different aged chicks....under the nest bench and under the poop board both come to mind as decent brooder spaces, but make sure you build in easy access for you as the keeper.