Can I change the default delivery method for 2-factor authentication codes from iPhone to SMS?

You can add your Android phone as a trusted telephone number, and can then sign out of the iPhone.

• Check your Apple Account device list to find where you’re signed in - Apple Support

See the section: About trusted phone numbers and trusted devices

Completely depleting an iPhone battery can brick the iPhone, as well.

As Mac Jim points out the 2FA code is sent to all the Trusted Apple devices one may have first, then if for some reason that code cannot be received, or accessed you have the option to send it to a trusted number immediately after the code is sent and you get the code entry screen.

How is it inconvenient, to simply let it send the code, and then just click or tap on the "Did not receive code" option to send the SMS, it's one extra step.

Also, when logging in to Apple TV or other services, you should set the web browser or device as trusted, so a code is no longer required and you can just sign in.

click here ➜ Use two-factor authentication for your Apple Account on iPhone - Apple Support

The first attempt is to a Trusted Device which is one that is logged into the account and would be your daughters phone and to use a Trusted Phone number you have to manually choose the option to send a Text Message. This can be an Android phone and would be the one listed as a Trusted Phone number on that Apple Account. It appears you already have your Android number set as a Trusted Phone Number and that is being used when you choose to send a Text Message. It will not automatically use the Trusted Phone number without you asking to send the text message.

No the 2FA provider picks the method. This is for privacy and security measures.

Do you own any other Apple devices such as iPad, Apple Watch or Mac?