At first, any specialist subject will have vocabulary you're unfamiliar with, but reading around a single topic - whether that's space or baseball or the Shinsengumi - will naturally build your vocabulary in that specialist topic.
I think you need to think more about what type of stuff you want to read. History = any sort of history? A specific period? You'll have more luck if you narrow it down. Would you search for "interesting video" in English or would you search for 'funny cats' or 'cake recipes' or 'best football goals'?
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I often search for a topic plus 動画 if looking for video
A topic plus 入門 or 基本 for "introduction to" or "basics of".
Add の or を to the search if you get too many results in Chinese.
For fiction I'd recommend not going for classics initially - I read a lot of crime/detective fiction in Japanese which I got into because someone was selling them cheap on Ebay - they're much easier, fun reads.