In the current version I don't think you have access to channel management, all that is done on the fly based on your first funding transaction and your capacity, rebalancing is the same, you just burn your capacity and then pay the rebalancing fee on the fly as you receive or send funds
I think if you want to have more access you'd need to spin up your own greenlight node with them first, but as far as I can see Green wallet doesn't have an option to connect your own greenlight node