It doesnt really need to be a text file if you can just separate the bounding box definition code to its own source/header file, or wherever that information can be hidden without getting on the way.

How is your game structured? The example you posted has some magic numbers (which should probably be defined elsewhere, maybe not in a separate text file but elsewhere in the codebase), doesnt have any vector class or bounding box class to make the operations neater, and the check against a single object in the scene has been hardcoded.

-Make a Vector class to represent positions, so you dont have to do everything 3 times once for each dimension.

-Make a bounding box class to represent bounding boxes for the same reason

(So you can do if (nuclearBunkerBB.contains(player.position)) to check if the player is in the box)

-Try to abstract the collision code such that all objects are treated equal if possible. Most objects probably behave pretty much the same regarding collision, so you can have a vector<Collider> which you loop over to check for collisions. If you need object specific collision responses, you can give each Collider a callback function or something similiar which allows you to implement these custom behaviors.

-Define the magic numbers and such so that the logic isnt filled with them. This is somewhere where you define what a nuclearbunker is, or what a player is. These definitions can be loaded from disk, or they can be defined in code (Eg you could do something like have a vector of object types, each one identified by some enum, and each object type tells its dimensions and any other relevant information)