Feel welcome Lululu
you´re not the first one asking this question and there are several topics around this question in this forum 
Here´s one example (about the FP3):
Wanna get more? Just try out that search funtion top right of this page
But also an honest answer to your question in a nutshell:
The Fairphone´s not a all-in-one device suitable for every purpose. The pictures it takes are quite good but if you´re looking for something better: Take a real camera
Yes, there are much more devices out there that can do better pictures, got more features, are cheaper, better, whateever.
Keep in mind: The Fairphone is a mobile phone with the idea of sustainability; no swiss army knife but a good allrounder.
I personally don´t think it can challenge an iPhone when it comes down to pictures and their quality but it got other qualities in it that easily outmatch an i(don´t-like-it)Phone
Best
DonFnord