Searches for new resonances decaying to two photons and a Z boson and a photon in the ATLAS experiment at the LHC are presented. The analyses are based on $pp$ collision data corresponding to an integrated luminosity of 139 fb$^{-1}$ at $\sqrt{s}$ = 13 TeV recorded between 2015 and 2018. Three independent searches are performed: a boosted resonance search in the diphoton final state probing masses between 10 and 70 GeV, a diphoton resonance search from 70 to 110 GeV, and a resonance search in the $Z\gamma$ final state covering masses between 220 GeV up to 3.4 TeV.
No significant deviations with respect to the Standard Model are observed and upper limits on their production cross-section times branching ratio are provided.