Chrome can warn you if the username and password you use to sign in to a website were involved in a data breach. This setting is turned on by default.
You can also use Chrome to check all of your saved credentials at the same time. Chrome checks your saved passwords and then lets you know if any of them were exposed in a data breach.
To check your credentials, Chrome first encrypts your username and password. Then it sends the encrypted credentials to Google for comparison against an encrypted list of known breached data. If Chrome detects a match between the encrypted sets of data, it displays a warning that prompts you to change your password. Google never learns your usernames or passwords during this process.