At the moment, there is no feature that can transfer model data directly from an old device to a new one.
(However, coins and paid items can be transferred)
You can still use the data on your new device though! Model data made with your old device can uploaded to VRoid Hub, and then you can call up those character models.
However, model data that has been called up via VRoid Hub cannot be edited on VRoid mobile. Thank you for your understanding.