Coinbase has two forms of wallet, and the answer to this question depends on which you're using:
- Coinbase Wallet is a self-custodial wallet that gives you complete control over your assets, and responsibility for your own seed phrase.
- Coinbase Exchange account(s) are the addresses that your purchased crypto gets deposited into when you buy on Coinbase. These accounts are custodial, meaning you do not have access to or control over your private key.
If you want to learn more about this distinction, see this Coinbase help center article.
If you're using Coinbase Wallet, you can import your account into MetaMask. You cannot import a Coinbase.com (exchange) account into MetaMask, since you would need access to the private key, which is something you don't have, as the Coinbase exchange accounts are custodial.
If you want to import your Coinbase Wallet account into MetaMask, you'll need to locate the private key, and then follow the instructions here.