first create a new game instance if you havent made your own yet. to do this go to your content browser and click the green add new button. then click the blueprints class option. in the search bar search for game instance and select the option below that says game instance then click select. name your new blueprint to something descriptive. now open the game instance blueprint. on the left side in the my blueprint tab look for where it says variables and press the + sign. This will create a new variable now name your variable to something like levelplayerlocation or something descriptive. go to the details panel on the right and change the variable type to vector. now you can close that blueprint and open your project settings (from main editor tab: edit → project settings). in the search bar search for game instance in the drop down here select the blueprint you just made. close project settings.
now this next step is slightly different if you are making your trigger its own actor or if your doing it in the level blueprint. I will assume its its own actor.
create a new blueprint actor (similar to how you created the game instance). open this actor and go to the components section at the top left and click the add component button. search for a box collision. with the box collision selected go to the details panel and scroll to the bottom. look for “on component begin overlap” and click the green button next to it. this will open the event graph. drag off the exe pin (white one) and search for cast to (have your player character class here). now connect the other actor pin on the begin overlap to the object pin on the cast node. this will cause the following script to be run only when the player enters the box.