There are several ways to determine if an option is under or overpriced, including:
Comparing the option's price to its intrinsic value: The intrinsic value of an option is the amount by which the option is in-the-money (ITM), or has value based on the current price of the underlying asset. For example, if you own a call option with a strike price of $50 and the underlying asset is currently trading at $55, the option has an intrinsic value of $5. If the option is trading at a price higher than its intrinsic value, it may be considered overpriced.
Using option pricing models: Option pricing models, such as the Black-Scholes model, can be used to estimate the fair value of an option based on certain assumptions about the underlying asset, the option's expiration date, and other factors. If the option is trading at a significantly higher price than the fair value estimated by the option pricing model, it may be overpriced.
It is important to keep in mind that these are just a few potential indicators of an overpriced option, and other factors may also influence the price of an option. As with any investment decision, it is important to thoroughly research and evaluate the risks and potential returns before making a trade.