Welcome aboard!
The tools and techniques differ based on the engine with which the game is built.
If the game is built with Ren'py (there will be a "renpy" folder and a "game" folder, and usually one or more ".rpa" files inside the game folder) then this tool
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can usually be used to do the job.
For a Unity-based game, Google "unity asset extractor" and you'll find several tools and a couple of Youtube tutorials. (I've used
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)
I'm sure there are similar tools for other engines - those are just the two with which I'm most familiar.