Alright, this isn’t gonna be as straightforward as you’ll want it to be. Two ways to do it:
1. Just change the flooring and size of the level of the ‘first’ level.
2. Set an invisible pressure plate actor directly underneath where the hero spawns in the ‘first’ level. Next, set up an invisible door in the level you want the hero to spawn in. Set the code in the invisible pressure plate to hero teleports to <door and level>. Have the invisible door not be hooked up to any other door.
You can usually get pretty quick responses in the Discord. Someone else there will probably be better able to explain it than I. I can try and make a video to demonstrate, though.