Decide what needs your approval

Open Menu, then SETTINGS, then Payments and communication, and look at the booking controls. The screen sums up its job as controlling what happens when a client books you online.

There is a separate switch for "Also instant-book new clients", described as people you have never seen before skipping approval too. The app is honest that most pros leave this off, and that is good advice: instant booking for regulars is convenient, instant booking for strangers is how you get a full day of people who never turn up.

Individual services can override this. Anything set to Always request waits for you regardless.