I have recently purchased a Canon 800D / T7i along with the bundled 18-55mm f/4-5.6 lens, plus the 50mm f/1.8 and the 55-250mm f/4-5.6 for myself and my 12-year-old daughter.
She has been using a Samsung Galaxy S8 smartphone for shooting her dog and this is going to be (at least initially) her main use of the 800D. You can get an idea of the types of photo she takes from here.
I don't want to let her use all 3 lenses initially because I don't want to overwhelm her. Since it is her first DSLR I would like her to get used to using just one lens before moving on to one of the others. My gut feeling is to give her only the 50mm f/1.8, but I would like to hear recommendations from experts.