Just research subjects that you're interested in!! ask yourself questions related to the topics of interest
the mostly you can find is in online resources, like websites, forums or articles

maybe a bit more unusual, but I tend to look up word synonyms/different meanings of the word
so while i'm writing, instead of using the word "engine," I might look up alternatives like "propulsion system" to add variety, and sometimes one thing can lead to another, and you can discover new concepts or ideas to incorporate into your story

I also like to take notes of possible ideas as I research, even if they don't make it to the final story
I hope that somewhat helps!