I want to keep track of my daughter's phone with out her knowing. What can I do?

I don't think you can. You can set up Find My friends but she has to agree to share her location with you.

Find friends and share your location with Find My - https://support.apple.com/HT210514

The other way might be for you to make her phone "yours" by setting up Find My on her phone with your Apple ID. Then you could track it with Find My and your Apple ID the way you would with a lost device. She could then configure other things with her Apple ID.

You can try Find My Phone, but you have to sign in with her Apple ID and password.

Find My Phone - If your device is lost or stolen.