Source: Google
With this new feature rolling out on Android, you can hide what you browse privately in Incognito mode. Google is bringing the option to lock your Chrome Incognito sessions behind biometric authentication. So, if someone's using your phone, they can't see what you browse privately. (Of course, they can see the tabs you have in the regular Chrome browser.)
When you have the feature enabled, you must verify your identity through face unlock or fingerprint every time you want to return to an Incognito tab after exiting Chrome or moving to another app. Google first started testing the feature on iOS. You can check if it's available on your Android device by heading into Settings > Privacy and Security > Lock Incognito tabs when you leave Chrome.