In the beauty sector ATLAS performs searches for New Physics (NP) effects by precisely measuring CP-violating parameters in the $B^0_s \to J/\psi \, \phi$ decay, branching fractions of very rare decays like $B^0_{(s)} \to \mu^+\mu^-$ and angular distributions in rare processes like $b \to s\,\mu^+\mu^-$. This report summarises results from the angular analysis of the $B^0 \to K^* \mu^+\mu^-$ decay performed with Run 1 data and projections for the $B^0_s \to J/\psi \, \phi$ and $B^0_{(s)} \to \mu^+\mu^-$ measurements for the Run 2 and for the High-Luminosity LHC (HL-LHC). The projections are based on extrapolations of the Run 1 results with the expected statistics corresponding to assumed 130 fb$^{-1}$ (3 ab$^{-1}$) of delivered luminosity for the Run 2 (HL-LHC) and on simulations of the expected layout of a new all-silicon Inner Tracker (ITk) for the HL-LHC.