Learn English – Is there such a thing as a sentence sign

No. The standard abbreviations are Ch. and Chap.

…or at least, if there is such a symbol, Unicode doesn’t know about it yet — and Unicode is pretty comprehensive, including characters as diverse as the inverted interrobang ⸘, biohazard sign ☣, and snowman ☃, not to mention the Shavian alphabet and much, much, much more.

Among the various words descended from the Latin "signum," an identifying mark, are signature, signify, assign, ensign, SIGN, all generally having to do with marking something with a practical label. For instance, a signature marks the authenticity of a document. A stop sign marks the intersection with a government mandate to bring your vehicle to a halt. A naval ensign is a flag flown from a ship to declare its military significance. The interpretation of a sign is usually assumed to be literal.

The word SYMBOL descended from the Greek "symbolon," sym, from syn = together, bol = thrown, hence thrown together. Symbol came to mean a representation of an idea. It's interpretation was intended to be metaphoric, not literal.

This distinction between conceptual ideas and practical operations follows logically to mathematics, where the overarching concept of notation as representational is called symbolic. Whereas the mark specifically directing each operation is typically called a sign.