How to change padding to 15 min after bookings - grid options cannot be found

We are a training organisation who currently uses 1 calendar in 2 booking pages (2 assessors), but we are moving to 1 booking page with multiple assessors who conduct sessions with students.
To avoid manual processes, we want to schedule 1 hour sessions with 15 minute breaks and occasional 1/2 hour breaks for lunch. We have had no success with adjusting the settings to make this happen and we definitely need flexibility in having the start times not on the hour.
I have even tried to use custom availability and add in breaks in calendar and adding time as ‘free’ for availability but to no avail. Your assistance is most appreciated.
Thanks, Brenda

@Brenda_TSA You can add a 15 minute break between bookings here:

For the multiple assessors it is best to invite them separately and connect to their calendar independently. That is done here:

Then we are looking at each of their calendars. They can add busy events for their lunches and breaks.