Apple would do well to have app limits turned on by default for particularly addictive apps like social media. Would love to see Zuckerbergs face if Apple shipped a 10 minute daily default limit on Facebook 😂
To set a per-app limit: Settings > Screen Time > [Your Phone] > Most Used Apps > Select app > Add Limit. It's a bizarrely complicated flow, but hopefully a future update will enable you to just set per-app limits under App Limits. Until then!