As of now, Coinbase does not support Binance Smart Chain. Binance Smart Chain is a blockchain that is designed to run smart contracts. It uses a Proof of Stake consensus mechanism. The Binance team developed this blockchain so that it would be compatible with the Ethereum Virtual Machine.
This would allow for a large number of dapps to be built on top of it. The Binance team has also stated that they plan to eventually support cross-chain swaps between Binance Smart Chain and Ethereum.