Right. Phonics is essential but it works best on words with fairly simple spellings. It doesn’t help, for example, with the multiple ways to pronounce “ough”. Those kinds of words have to be memorized so they are recognized by sight. (Or is it “site”, or is it “cite”?). Of course, when a person has true fluency of reading, it’s all by sight.
The silent letter rules and the substitute letter rules.
You will find them in readers from the 1830s or so.
Using those rules you can figure out how to pronounce most English words.
We used them when homeschooling.