For some reason, Text to Speech has a text limit, which says partial part of the text, and not the full way. Text to Speech requires internet as well because it doesn't have a built-in text to speech sound, it is stored on their server or their programming language. However, there's an alternative that can say the full thing, here are the examples…

Text to speech: Say [Hello, I speak too much since I am very chatty, I work on Scratch and I help]
Text to speech: Say [projects speak, I am an extension of Scratch, and I'm here!]
// Break up text to say the whole thing...