I'll echo what others have said here. As long as she has
a camera, be it her phone or whatever, she should focus on learning about the rules of composition and some of the basics.
But I'll tell you from my personal experience, I quickly outgrew my phone and subsequent digital camera, and upgraded to a crop sensor DSLR (D5100). My main issue was the photos had a delay between pressing the button and taking the picture, which I hated. And then I didn't outgrow that camera for about 6 years, which is when I started doing more weddings and events and needed a full frame camera for the sensor.
Without an idea for your budget, here is my sub $1200 "starter" kit (bias towards Nikon, and refurb) that I recommend to people interested in portraits and general photography (and I made it easy for you with Amazon links):
The idea here is to get the basics, so that she can try a wide variety of photography types (portraits, wildlife, landscape/astro, macro, etc), and figure out what she likes best. You can also just get the camera and lenses and not worry about lighting, but it depends on her interests. The goal is to keep shooting as much and whatever she can. Experience is the best teacher.
Whatever you decide, have her post her pictures here (or post them here for her) so she can get feedback and critique on her work.