/portal create name: desti: triggerblock:

Creates a new portal after first selecting an area with a Portal Region Selector tool.
The parameter triggerblock: should be set to whatever block will be inside the portal gateway. e.g. NETHER_PORTAL
Use an additional parameter permission:<PermissionName> to restrict who can use a particular portal.
Use an additional parameter bungee:<ServerName> if the specified destination is on another server within the Bungeecord/Waterfall cluster.