Yes — "not" is a Dolch Pre-Primer sight word. It follows regular phonics rules, but it's taught for instant, automatic recognition because it appears so often in early reading.
This is not my hat.
"Not" is a fully regular short-o word, but it's such a common word for saying "no" within a sentence that it's taught for instant recognition, rather than decoded fresh each time.
"Not" is fully decodable, so it's also a solid word to practice sounding out once it's recognized by sight.
Word Wizard teaches "not" with Flash Cards, Listen & Pick, Spell It, and Write It — four game modes that turn repetition into play.
See "not" with its picture, syllables, and example sentence — with native audio.
Hear "not" spoken aloud and pick it out from similar-looking words.
Build "not" letter by letter from shuffled tiles.
Word Wizard turns sight word practice into a game — Flash Cards, Listen & Pick, Spell It and Write It, from Pre-K through Grade 5.