How to dynamically create GameInstances on a dedicated server

Hello Guys,

I am trying to set up a lobby on a dedicated server that players can join and then start a game from that will be hosted by that very machine (talking about 1 - 3 games at a time).
My idea is that if a player wants to start a game, the server generates a new instance of the game using the parameters given by the player.

My question now is:
Do I have to start the parameterized Server.exe from code or is there a engine built in way to generate multiple gameinstances ondemand.

thanks & greetings,