This reminds me fondly of things I used to do for programming contests :)

I think I did an anagram dictionary once. My memory is that I computed the anagrams once ever and made a dictionary file which was a sorted word list and the offset of the next anagram of that word. The sorted letters for each anagram group were also in the same list. Because it was searching for multiple word phrases you just did a search on the subsets of letters left for candidates.

Scrabble dictionaries were the most mind bending I think. I don’t think I wrote anagrams up but this is the scrabble one https://williame.github.io/post/87682811573.html