Do not disturb for 15 minutes

Hello clintb1026,

On your iPhone you can set a schedule for a Focus: Use Do Not Disturb with Focus on your iPhone or iPad - Apple Support

You can also set a schedule on your MacBook Pro: Turn a Focus on or off on Mac - Apple Support

It does not appear that you can change the 1 hour preset. You can leave Feedback here: Product Feedback - Apple

Take care.

I suspect there may be a way to do this using Shortcuts, though I couldn't give you specific directions. See here:

Shortcuts User Guide - Apple Support

Also, you may be able to do an internet search something along the lines of:

"iPhone shortcuts focus duration 15 minutes"

Or something similar.

There are examples of shortcuts out there.