google search – How do I block websites that contain specific words or phrase?

I need an extension/software that blocks pages based on the basis of words from the body of the website

The extension or software must to be free to use, and preferably come with password protection and an option to whitelist some websites

Extensions like ‘blocksite’ just looks at the page URL and title, so is quite ineffective as it lets me bypass this just by a deliberate misspelling or another closely related word (Even if I block the word ‘Harry Potter’, I can still get through by searching for ‘Hogwarts’ or by misspelling it as Hary Potter ) .

{An extension by the name TinyWebfilter did this perfectly, but it was removed from the chrome webstore}

I would be highly obliged for any help