Is fire extinguisher example of Charles law?

No. Charles Law describes the relationship between a gas and temperature. (gases expand when heated)

You are thinking of "Boyle's Law" which is the relationship between a gas and volume and pressure. With the fire extinguisher example, a lot of the gas (even though its a mixture of chemicals, it behaves like a gas) is compressed into a small volume and so when you pull the handle, you give it room to expand and it shoots out until it reaches equilibrium.