Well-being
Limits you set for yourself: a daily post cap, a screen-time cap, and a downtime window.
Settings, then Well-being. These are your own limits, not a guardian's, and they are deliberately gentle: the pause is the point, and you can always continue.
Daily post limit
Cap how many posts you see in a day: 50, 100, 200 or 500, or off. When you hit it, Surf tells you rather than quietly continuing.
Screen time
Cap daily use at 15 minutes, 30 minutes, 1 hour, 2 hours or 3 hours. Continuing anyway defers the limit for ten minutes before it can trigger again.
Downtime
Set a window during which Surf asks you to stop, for example overnight.
These limits are held on your device and a determined person can lift their own. That is the design. A limit that fights you is a limit you turn off permanently after a week.