How do I control my phone through my iPad

You don’t. You can have the same apps on your iPad and use them on either device, but iOS doesn’t offer any remote control features, as it would be a security vulnerability.

Hi ardita129,'

I don't think this is a feature on either iOS 13, or iPadOS 13. However, if you lose your iPhone or iPad, you can remotely put a passcode on it in the Find My app. The Find My App is a default App, developed by Apple for both iPad and iPhone, along with many other of their products.

I hope I could help,

brandonbng