It's not currently supported. The main barrier to this is the high complexity of doing this. Your game would have to pick a peer, figure out how to transition the game state from peer-following-host to authoritative-host mode (e.g. by switching which event groups are active and transferring all other state used anywhere for any purpose in your game, including variables, behaviors, and so on), reconnect all other peers to them (if actually possible), and then resume the game once everyone is connected again (if everyone actually made it). It's the switching a peer to a host part that is probably toughest, will be a real headache to figure out, and if you make any kind of mistake your game will have weird bugs after the switch.
A better approach is probably to use a centralised model instead, where a permanently running server is acting as the host.