Just set the Level loading setting to Blueprint and trigger the change in the Level Blueprint: https://blueprintue.com/blueprint/geo4l8hz/

I'm sorry, could you please explain in more detail how to use it? I've created a new level and added several completed levels to it. After that, I pasted the code into the level blueprint, but it keeps failing after clicking 'cook content of aximmetry de'.

I don’t know how much clearer I can make it. There are numerous tutorials for loading levels through blueprints, it doesn’t have to be specifically for Aximmetry. 

If you read the cooking error log, you will find information about why the cook fails.

Did you actually change the references in the blueprint to the levels in your project?

side topic: when using sets with multiple levels, do you notice a performance difference vs having only 1 level per project? say you want to make 10 possible interview setups to switch between, having them all as separate projects vs all 1 project in separate levels

Hi Darren,

You shouldn't experience any performance difference, no matter how many levels you have in your project.
Only the size of your project folder, the cooking time, and how fast the compound starts could increase.

Note, that if you use async level loading instead of Open Level, then you need to close the previous levels.
Also, if your level has programming problems like memory leaks, that can affect other levels that you load afterward. This is however a problem that will affect you anyway.

Warmest regards,

Thank you, I succeeded, but in ‘Aximmetry’, only the first time I press the ‘trigger’ can I switch, and then press other triggers, it will fail. Is there a solution?

Hi 5750Arvin,

Each level has its own Level Blueprint. So you need to copy the same blueprint logic into all your levels for it to work in every level.

Alternatively, you could use Persistent Level: https://docs.unrealengine.com/5.2/en-US/managing-multiple-levels-in-unreal-engine/ 
And then you only need to have the level loading blueprint logic in the Persistent Level's Level Blueprint.
Note however that Persistent Levels are more complicated to handle, for example, you will need to unload levels.

Warmest regards,