People use their phones too much and find it hard to reduce their screen time
One Sec adds a pause before selected apps are loaded to help users be more mindful of their use.
https://www.flinteger.com/products/omnilock/
Uses the Screen Time API to enable users to block certain apps easily
While being more of a “focus timer” app and not a generic screen time app, they also use the tactic of enabling users to put money on the line to encourage themselves to refrain from using the phone, I found that really interesting and might copy their UI for it.
They also use a visualization of a tree growing when you stick to your goal and tell you you killed the tree when you fail, which actually feels pretty bad.

Raising the stakes.
Help users overcome their habits by making it painful to overuse their phone.
User set a usage goal, and a price to pay for failing to meet the goal. If they fail they pay.
This helps users be accountable and think twice before ignoring their screen time limit.
Possible alternatives:
Number of users that use the app to set a goal and put in credit card