Delayed charge (waiting to charge fully or charging the last ~20% slowly to just-in-time for your alarm) is a different setting, though I don't recall the name for the "Only charge to 80%" one
> To change your charging option with iPhone 15 models and later, go to Settings > Battery > Charging and choose an option. You can choose a charge limit between 80 percent and 100 percent in 5 percent increments.