You have two ways to code it all:
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blueprint actors that have triggers message and all that, use either components or function library for interacting with player. And this way after 10-20 lines will be nightmare to maintain and improve. Simple code but gets really messy really fast.
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separate data from code. Use something like json to keep all your quest info in single text file. There are some plugins to read and parse json on marketplace. You also can make your own C++ plugin, its not that hard, buy some plugin for unreal that you can use and modify C++ source. Add your functions there.
You may find this inspiring:
And famous gaslighting AI: chatGPT, it has SDK now, so maybe after making it all work like in above movie, you can improve game with chatGPT and react to messages written in human language.
However remember that using such tech (that is not yours) you risk of THEM turning it off some day, and your product/game will become obsolete.