Is the 'Apple' message about my lost iPhone 12 a scam?

It is absolutely a scam.

Apple never sends such messages, certainly not ones with requests for you to enter Apple Account information,

The message is from criminals. They want your Apple ID and Apple ID password so that they can do one of more of the following:

• Clear Activation Lock and "make your phone their own"
• Ransack any of your data that is synchronized or backed up to iCloud
• Change your Apple ID password, mark your other devices as Lost, and use Activation Lock on them as a means of extorting ransom from you, the owner

Do not fall for it. Do not interact with the message or its sender in any way. Expect more such messages to follow – as the criminals continue to look for ways to get an unearned payday at your expense.

Well, if the message is correct, you will be able to locate your phone using Apple's Find My application, so you don't need the information from Google.....which appears to be a scam because you are being asked to enter your Apple ID and Password

Try to log on again using Find My on another iOS device or a computer

Enter your Apple ID and Password

Does your phone appear in Find My? If not, what message appears?

No Device Found?

Offline?

Something else?

If you see an Offline message, there are several reasons for this:

The battery has run down

The phone was powered off

The phone does not have a good Internet connection where it is located

All that you can do in this case, is keep trying every few hours to see if the phone's location appears.

Remember that Apple does not get involved with lost or stolen phones, so any message from "Apple" or "Apple Support" is very likely a scam that is trying to trick you into providing your personal details to allow whoever has the phone to get into the data on your phone.

If you feel a need to check Find My, use the Find My app on your (remaining) Apple devices – or log into the Find My site on the Web following Apple's instructions.

Use Find Devices on iCloud.com - Apple Support

Do not click on any link you get in a text message or e-mail. It is far too easy for criminals to send links that take you directly to bad places (that may be disguised with graphics "borrowed" from legitimate sites).