This is still a work-in-progress feature, if you’re an Unlimited subscriber you can enable it under ‘Settings > App Preferences > Feature Previews’. Please leave your feedback over on the Community Forum

Press cmd/ctrl+E and select a couple cards, or enter the ‘Multi-select mode’ by pressing the button in the Noteboard options menu. Modify visibility, targeted date, colors, and add tags or parents for multiple cards at once.