There are several ways to trade volatility index, such as:
Buying and selling futures contracts on a volatility index such as the VIX
Trading exchange-traded products that track the VIX, such as VXX or UVXY
Using options to trade volatility, such as buying or selling call or put options on a volatility index.
It's important to note that trading volatility can be risky and it's important to understand the underlying mechanics of how these products work before trading them. Additionally, it's important to note that volatility indices such as the VIX are derived from options prices, they don't always move in the same direction as the underlying stock market. It's always recommended to consult with a financial advisor before making any investment decision.