How can I create a shortcut to toggle on/off on iPhone?

You can’t automate powering your iPhone on when it’s off.

You already have a shortcut for powering your iPhone off:

Simply swipe down from the upper-right corner of the display and you will find a power button in the corner. ⇣

Good luck! 👋🏼😉

Most carriers support using a code in the dialing sequence to suppress the caller ID for a single call...

*67 in the US and Canada or 141 in the UK at the beginning of the number being dialed will hide your caller ID.

If you have caller ID disabled and want to show it for a single call, *82 at the beginning of the number will display your caller ID.

Note that you can NOT hide your caller ID when calling toll free numbers and most government and emergency service numbers. They will always see the caller ID info no matter what.

To toggle what between on and off?

You mean you want to create a shortcut to shutdown the phone?