As of now, Kok is not on Coinbase. Kok is an ERC20 token on the Ethereum blockchain. It is however, listed on a few other exchanges such as Binance and Kucoin. Coinbase has been known to list ERC20 tokens in the past.
So, there is a possibility that Kok could be listed on Coinbase in the future. However, there is no guarantee that this will happen.