Hi alon198,
welcome to the Apple (user-to-user) Community!
Re: Voice trigger for Casper bed presets on iPhone
Am no expert in this area, yet, with your kind and thoughtful assistance to the other person in mind, your request surely deserves some response. We don't know your level of expertise, so please excuse if any or all of the info. below using Apple Support's documentation is not needed. If so, then let us know more about your needs.
It may be worthwhile to check the person's iPhone is updated to the newest compatible iOS version first.
(You can check in Settings > General > Software updates, to see if updates are available. NB: It is wise to back up the iPhone's data before updating: If needed: How to back up your iPhone, iPad, and iPod touch - Apple Support )
Then ensure the correct iOS version shows, or is chosen, at top of any articles below for accurate info.
I'm guessing the Casper bed is able to connect either wired or wirelessly to the iPhone, for control.
There may or may not be an app available to install on the iPhone, and which may or may not provide some controls.
See how to: Use Vocal Shortcuts on iPhone - Apple Support
More info. on how to: Use Voice Control on your iPhone, iPad, or iPod touch - Apple Support
This Voice Control video on making custom commands may be helpful;
https://www.youtube.com/watch?v=KCUpc-OXUJU
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Else: For creating iPhone Short-cuts, Apple provides a user-guide: Shortcuts User Guide - Apple Support
You can click on "Table of Contents" at the top of the Welcome page.
This leads to various topics, and related articles to assist with creating and using shortcuts.
To ensure accurate info: You can choose the correct iOS version at the top of articles.
The search function is always available to help zero in on related articles.
Eg: For personal automation:
Setting triggers in Shortcuts on iPhone or iPad - Apple Support is likely to be a useful starting-point
and other articles may help with the finer details:
If you need assistance with accessibility features like "Voice Control" you may want to reach out to Apple's Accessibility Support Team:
Eg: from Apple's Accessibility Support Website: You can "Get Support" (online chat / phone / email etc.) from the link at the bottom of their website: Accessibility Support - Official Apple Support
All the best :-)