thanks for your request!
There is a reason why changing the z-order is not supported with cocos renderer: in Cocos, changing the z order is a very complex operation and is not supposed to be publicly available. The reason why it’s complex, is that the scene graph is stored as a z-ordered list, which would need to be re-sorted during runtime which is not efficient.
If you provide details what you are trying to achieve, I could point you to other approaches to meet your desired goals. In general, you could add some parent items with different z orders and add the children to the z-order where you would want it to be.