Global variables aren’t really a concept used in blueprint. BP is based around references and interfacing.
The best thing you could do is add a GameInstance blueprint and add it to your project. Put variables you want to be global in the GI BP and you’ll be able to access them from anywhere at any time. Just “Get Game Instance” and cast it to the type of GI you created and access all of your variables from it. The GameInstance is created and destroyed only once, so it will persist for the life of your game.