Dictionary/ Synonyms + Spellcorrect

So firstly not sure if maybe I’m missing any of these things, but if not, I think it would be awesome if there was a built in dictionary as well as a built in thesaurus where you can just highlight a word and get alternate options for words.

Also I have been having a lot of red squiggles appear for misspelled words, I’m not finding any quick functions to correct the misspelled words. (I.E. Google docs right click brings up the correct spelling). Maybe I am missing it?