I'm glad to discover that I'm not alone in that, "Hmmm, I wonder if my internet history has put me on all of the lists yet?" reading pattern. On Wikipedia especially, the fun is opening an endlessly nesting series of related topics. Sometimes that can get... weird.
That is a great attitude, and it not only helps you (by being more knowledgeable and less worried about hypotheticals), but also the rest of us by reducing effectiveness on the profiling of those who read certain things - the same way that being a normal person that uses tor reduces the "use tor"="pedophile" fallacy (and substitute tor by end2end encryption, torrents, decentralised communication, or what have you).
Researching chemcal weapons on wikipedia wont get you on any list. Asking people where you can buy the needed stuff, THAT is list worthy.
Anything on wikipedia was put there by someone. That someone is far more suspect than the readers. Material that is actually dangerous is quickly edited away. Unless you live somewhere properly dangerous or are already on a list. Such people should probably stay away from the internets all together as almost anything found online can be made to sound evil.
I somewhat lost of my fear of this when in my late teens I became fascinated with these[1] and basically read everything I could find about them, including poking around LANL's website enough to spelunk a PDF of their paper about construction methods
This lead down a rabbit hole of reading about all of the types of military-grade explosives available & their yield and discussing creative scenarios to exploit EMP weapons with friends online.
Not on the no-fly list or any watch-lists (that I know of) yet.