How can I find my daughters location without her knowing

Not sure which tracking apps for iPhone could do this as you wish.

A few different named product apps &/or services appear in search:

https://duckduckgo.com/?q=parental+tracking+app+iPhone+by+number&t=ffsb&ia=web

There are some worth checking further into who their makers are &

what they propose; and how these may affect your own security.

Some likely work a bit different than the other. Like with all things on

the internet, I'd be careful to research the sources of these apps and

any/all the information they'd want to control in order to 'help you' do

what they say can be done. Be aware some aspect of security setting

may be asked by these software makers to be changed for it to work.

And I have no recommendation; even items in the App Store may (or

may not) yield best-world results in the real world.

Good luck & happy trails! 🙂

How do I find my daughters location by her number without her knowing?

I believe any app's ability to track a phone's location is wholly dependent on the trackee's knowledge.

Would you want an app to have the ability for anyone using said app to track your daughter without her knowledge?

This is a key feature of iOS. Privacy in the control of the user.