Higgs boson decays to two photons can be selected with high efficiency, and the very good invariant mass resolution allows a robust subtraction of the backgrounds. These proceedings present measurements of differential cross sections, as well as cross section measurements for the different Higgs boson production processes in the simplified template cross section framework using pp collision data collected at 13 TeV during Run-2 operations of the LHC with the ATLAS detector. The differential cross sections are interpreted in the context of an Effective Lagrangian to set constraints on possible new interactions of the Higgs boson with the Standard Model particles. Moreover, the differential measurement of the transverse momentum of the Higgs boson is used to set limits on a possible modification of the Yukawa coupling of the Higgs boson to the charm quark.