How Does the Total Premium of an OTM Option Relate to Its Time to Expiration?
The total premium of an OTM option is entirely composed of extrinsic value. This extrinsic value is directly related to its time to expiration: the longer the time to expiration, the higher the premium.
This is because more time increases the probability of the underlying asset's price moving favorably to make the option ITM, and it also increases the compounding effect of the risk-free rate.